Thats the point, it doesnt matter if they do or dont.
If you read through their post history, they have a comment or sentence for almost every possible reason:
Difference in vision
forcing development to fast
Didn't listen to safety concerns
Lying about finances
Making deals without the board
Hiding financial matters.
It is like someone is rattling off the top 10 guesses for the reason from HN or predication markets.
Now if they said something like Ilya Sutskever called Sam at 1215 on hangouts to tell him, That would be a be pretty solid proof.