"I said to someone a few years back that the only guarantee in this game is that you'll get sacked at some stage. In the end I resigned, but I wasn't prepared to work within the parameters that they [the union] were trying to put in place," he said.
"When those stipulations have the huge potential to create stress and affect my family then it's something I wasn't prepared to be part of.
"I'm hopping off the conveyor belt with no idea when or where I might get back on ... I honestly can't tell you what [the union's] motivation was for readvertising my job, although I have a few personal thoughts [but] a review process that takes two months to complete before they decide to readvertise means obviously they're looking for someone else."
Although there's been plenty going on behind the scenes, including plenty jockeying and politicking for Horan's job, a falling-out between Horan and assistant coach Paul Feeney and a failed bid by Horan to win the Wellington Lions job while negotiations for a further term with the Steamers were in limbo, he was ultimately undone by one thing - Bay of Plenty's determination to slash budgets for next year.
It might seem trivial, but following his end-of-year review Horan's new contract - the one he ultimately didn't sign - proposed to cut his salary and give the Steamers less money to work with next season.
It was untenable, he said, particularly with Bay of Plenty again expected to finish in the national championship's top four. "I met all that was required of me this year, met the four KPIs [key performance indicators] and got paid all my [KPI] bonuses 100 per cent when I left last week yet this was the first year with the Steamers I'd never had my review professionally outlined.
"My first meeting [with chief executive Mike Rogers] there were a few stipulations around personal development and a development plan with a couple of staff that I could barely live with, but where the whole thing unravelled was that I wouldn't agree to stipulations that included giving me less money and less control as head coach-director of rugby without consultation, all by someone who doesn't know how rugby runs professionally.
"I'd been there when the union was insolvent, I'd been there in '08 when the team cooked its own meals and bused places because we couldn't afford to fly and yet they wanted more but wanted to pay less next season.
"I wasn't prepared to stand up in front of guys like John Pareanga, Culum Retallick, Lance MacDonald, Tanerau Latimer and Luke Braid - guys who were there in '08 when we constantly overachieved given our level of resourcing - and deliver them that news."
Horan found it particularly galling to be told he was a victim of his own success.
"It was like 'here's Sean, he's been here for a while, he'll be alright if we cut the bottom line but keep the same [performance] KPIs in place. I wasn't going to stand by and let that happen."
OF his falling out with Feeney, who stepped in late when Horan's assistant Steve Miln left to go farming, all Horan would say was it was fraught from the start and another example of the union saving money, with Feeney already on the payroll in a high performance role.
"It was a forced marriage because of finances. Milny left, and with it went the cost of his salary, car and phone. Rat [Feeney] was there and ready to be used in a dual role, I had to accept it... but I'm not God, I'm not going to slay him and anything that went on is between me, him and the team."
One Bay player, speaking on anonymity, confirmed the tension between the two coaches, saying it was even more evident after the mid-season loss to Auckland which put the team in a losing spiral that would cost them a place in the ITM Cup playoffs.
"Sean was good but if you know the way he coaches it's intense. The biggest drama all year was him and Rat - they didn't see eye to eye and it was very obvious.
"Sean's such a dominant figure who doesn't like being undermined, his way or the highway sort of thing. Rat's one of the best coaches I've had in terms of a game plan and drills but there was no middle ground between them and who's to say who's way was better.
"Losing that game to Auckland we got ourselves in the s*** and it was the breaking of the season, putting more stress on their relationship. Some of the boys were happy with Sean, some weren't, but I don't think he needed to go. The union just needed someone in there to mediate between two guys who were stubborn and pigheaded."
There's plenty of behind-the-scenes rumbling for the Horan's old job. Applications close next week, with Feeney in the hunt along with others including former coach Kevin Schuler, Counties-Manukau's Milton Haig, dumped Hawke's Bay coach Peter Russell and locals Clayton McMillan and Darrell Shelford.
Horan is adamant Bay punched above its weight and said if he was unpopular with some of the players it didn't bother him, although he says he was respected.
In 2006 he applied for the head coach's job but missed out to Andre Bell. Two seasons later he applied again and missed out to Waikato's Greg Smith, although the job was soon his anyway when Smith was sacked five days out from the start of the season.
"In '09 I was told I didn't interview well yet Milny and I were the ones they turned to when it became a shambles. I was blamed for Smith's ousting yet I told them at the time it was a mistake because Greg was good technically but that's it. We'd turned our back on the Steamers culture, imported too many average players and staff and the culture had gone."
HORAN almost chucked it in at the start of Smith's brief reign but was talked into staying by the players and staff. He's proud of what he subsequently achieved against provincial heavyweights, particularly this year, Bay's second-most successful in 100 years.
"We were growing. Our recruitment and retention's smart and we base a lot on character and guys wanting to be there, good cats who want to work hard and learn every day.
"I've helped put systems and processes in place that will set us up for many years to come, which is why it's so gutting to see what's transpired."
Horan was talked into applying for the Wellington vacancy knowing that Chris Boyd would get the job. Contract-less and still in limbo he didn't tell anyone in Bay of Plenty he was applying. It didn't go down well when word got back and he got a terse phone call as he walked into his interview in the capital. He's unrepentant.
"I made it clear I wanted to stay in the Bay, even though I grew up in Wellington and played all my rugby there. Wellington were aware of my position but I did it as much for personal development as anything else and I'm pleased I did. So I chose not to tell anyone, but I stand by that [because] the feedback I got from the NZRU and Wellington on the way I interviewed was good, plus it helped identify other opportunities."
Horan has no next move beyond spending summer with his kids and wife Jacinta who owns a busy physiotherapy business and works with New Zealand Athletics and the world champion Black Ferns.
But there's a hole there that will take a long time to fill.
"I love the Bay and already I'm missing the Steamers immensely, which is probably normal when you bleed for something for five years. But I've never done it for the kudos, it's been about the players.
"If, in 20 years, I bump into a guy like Taniela Moa and he says thanks for reigniting my career, helping get me back into the Tongan team and helping me pick up a good contract in France then that's all I've ever wanted."