Who really knows what happened with that situation.
I think what happened is he had a messy ownership situation and no job security and felt the Lakers package was significantly better than the Clippers package even though it was the wrong direction to go. I'm not ready to fire him over it or anything, I just think the Lakers deal would have been employing the wrong team building philosophy even if in the end it could have potentially turned into say CP3 for Scola and Harden. That's not as good as Gordon, Aminu, Davis and Rivers, but that wouldn't be a terrible return on CP3.
Also, for those of you saying no one should complain about Thornton I beg to differ. In a vacuum I consider Landry for Thornton a fair trade, but you should get more than 3 years of usefulness out of a fringe starter level player that you draft. Thornton for 2 years of Landry makes it a bad trade. It'd have been better to swap him for another young up and comer.