1. They say they fired him because of his attitude/demeanour: But his demeanour was known 6 months ago when they could have fired him (and apparently discussed doing so, but decided not to).
2. They could say they fired him because of his record: But they hired someone who was directly involved in the accumulation of his record.
3. According to Anselmi on the Fan 590, they (the board) wanted to hold interviews for the job but he had to tell them that the time was not conducive for a search since the team needed to play next week and needed someone in place now.
All of that screams to some type of incident taking place which caused this to occur.
You might argue it wasn't the Luongo issue. You might be right or wrong, but some of his friends have said it was the issue. Either way, something must have happened.