Hastings Mayor Lawrence Yule, an amalgamation supporter, said the meeting was disappointing, in part because "a lot of the stuff that was given to us we already knew" and he saw no reason for keeping it closed.
Mr Yule said one disappointment was that Mr Nicholson had not read the Winder report, a 2012 study into Hawke's Bay's path to economic prosperity which was commissioned by the five councils as a starting point for the amalgamation debate.
"Everyone [at the workshop] was respectful and it was good to get together but in reality different councils have got different positions and the ability to get everybody together to adopt a common position is nigh on impossible I would think." Napier Mayor Bill Dalton, who opposes amalgamation, said the day had been positive and informative with Morrison Low providing details on the amalgamation experience in New Zealand and Australia.
"That was the whole point of the exercise - to learn what has happened around amalgamations around Australasia. The only way we can learn is by past experience.
"The reason why these people haven't read the Winder report is that there are people who don't read fiction.
"The Winder report is the most lightweight, useless piece of information that has been presented to councillors in my time. I cannot see how reading the Winder report would have made them any better informed," he said.
"The reason the press weren't invited was that we weren't going to provide a forum for show ponies and we wanted this to be a serious discussions about amalgamation and the effects it has had where it's been applied."
Mr Dalton disagreed with Mr Yule's view that everyone at the workshop had been respectful.
"It was a positive day until the conclusion of the meeting when Lawrence stood up and was rude to the presenters and stated very clearly that he didn't want to be involved in future discussions around amalgamation."
Mr Yule said he had told the meeting that because different councils had opposing views on amalgamation he believed the value of coming together in such a forum was limited.