[Havoc]

>Disallowing such collaboration is

There wouldn't be much of a collaboration if people bail or a bad incident happens at the conference.

The fact that multiple people went out of their way to warn the conference organisers suggests this goes well beyond a normal difference of opinion.

In that context it was a difficult but correct call in my opinion.

Plus frankly if staying away from such people is uncivilized, then I'm ok with being uncivilized.