The booster and his wife may be to blame. But, considering it wasn't some random incident but a guy he knew and should have probably known might be out to get his goat, O'Neil should have handled himself better. That is what you expect of your head basketball coach at the D1 level.
But then, if the guy you hired (I'm sorry, Pat Haden didn't hire him) as your head coach is a jack***, what CAN you expect, really. When your (former AD, and Heisman winner Mike Garett) AD is a jack*** and he hires Lane Kiffin and O'Neil, well, you'll have some cleaning up to do after those guys, one way or another.