Champion jockey Michelle Payne said that State Of Rest had moved across "three quarters" as it was revealed that a protest would be upheld.
Anamoe jockey Craig Williams did ultimately protest the result.
While McAvaney said that he couldn't remember another protest being upheld in the race, Payne said that she believed it would be overturned.
"I think the key factor is that Anamoe was making up the ground until he actually got bumped and then it stopped his momentum from picking up the ground he was making before that interference occurred," she said.
"It crowds his whip space, which I think Anamoe's - we're in the final stages of a race and he's definitely, you know, shifted in. It's against the rules of racing. Definitely makes contact and puts him off his course. So I'm leaning towards it being upheld."
The longer it took, McAvaney came around to the argument that it should be upheld.
But as the decision was revealed that the protest had been dismissed, McAvaney said that the result would continue to be debated for years to come.
"It will be talked about forever, it was such a close call," he said.
"It's one for the ages in so many ways. One of the greatest contests we've seen in a Cox Plate. We've seen so many over the years it has had the most controversial and divisive ending to any Cox Plate that I've ever witnessed. One that will be talked about forever and ever."
It continued a dramatic Cox Plate that saw favourites Gold Trip and Zaaki scratched from the race.
On Saturday morning, trainer Annabel Neesham confirmed British horse Zaaki would not take part in the event.
"Absolutely devastated to report that Zaaki had been scratched from the Cox Plate due to an elevated temperature. Gutted for connections and James McDonald," she said in a statement.
TAB bookmakers were so confident Zaaki would take out the Cox Plate, they paid out the triumph last month.
Earlier on Friday, Gold Trip was scratched from the weight-for-age race due to lameness in its legs.