That was a straight up, textbook definition of a flagrant one. That is why they have the option to call a flagrant one or a flagrant two. A hard playoff foul that goes as a flagrant one. As a basketball fan I'll be upset if they review it and suspend Howard. I don't want to be an NBA fan where that foul gets you suspended.
As I said in the game thread, you can't compare that to KG on Q-Rich. The league looks at basketball plays and non-basketball plays differently. KG's elbow was in a scrum. They view an elbow as equal to a punch. He didn't get a flagrant or anything, he got T'd up and tossed. Totally different and different situations. If anything the Howard play is closer to Rondo/Brad Miller, a play on which a flagrant wasn't even assessed.
Paul Pierce in his postgame press conference said himself it was a hard playoff foul, no one deserved to be ejected for that. I'll take his opinion as the man who got hit as holding some weight.