[BCF4L]

He didn't just hang on the rim, he also did a chin-up and kicked his legs out. If he had just hung on the rim I don't believe the ref would have called the T.
I don't agree with the call because it's called inconsistantly, but the chin-up is what resulted in the T.

He didn't do a chin-up. He was running in full speed and dunked it. Had he let go of the rim, he would have ended up doing a backflip because his momentum would have caused him to do so. Go back and watch it again. He ended up parallel to the ground because of his momentum after the dunk. What he did was the only thing he could do to keep himself from getting injured, which is what the rule states in the NCAA rulebook about technical fouls while dunking.