I agree with the flagrant call, but I wouldn't necessarily call it dirty, but it was at least reckless.
What I would support though, is that the player is not allowed to play for the duration of the other player's injury (obviously, up to a degree). If it is a legitimate flagrant foul, with no intent on the ball, then there should be some consequence for the offending player. The problem with this would be quantifying the extent of the injury.
Sure he was protecting the paint, but a collapsed lung? Gerald Wallace is a lot lighter than Bynum, but he is still 6'6" or so, and is a solid athlete.