Refs don't care, he's near the top of their list.
It actually takes Joey Crawford, the king of controversial calls and calling attention to himself, to give him flagrant.
It's the refs JOB to stop this stuff and keep it from escalating. I saw Wade pull down Pierce while they were in the air TWICE in that game before he pulled down Rondo and dislocated his elbow. He shouldn't have even been in the game at that point, but the refs just look the other way and say "play on." Until the Celtics actually start sticking up for themselves of course.
You foul Wade and he's taking you down with him. Say something back to him when you get up and he's still in your face talking smack, and you get a tech.