No, Pouncey was kicking a player who was unable to defend himself because he was trapped under an offensive lineman (who actually was protecting his QB). He earned his ticket to the bench, just like Garrett.
Whether Mason's hand was trapped in Garrett's facemask or not, following him and running his mouth was, at the very least, not smart. When you're starting because your starting QB is out, you have to be smart enough to avoid putting yourself in a position to get hit on the melon with your own hat--and he's lucky that he caught the open end of the helmet instead of the crown.
IMHO, Rudolph should've had his wallet lightened for his role in that. If he doesn't keep following and running his mouth, that helmet doesn't get swung at him.
And Baker was right in his post-game interview--it was inexcusable. It was stupid and it hurt the team, not to mention leaving a bad taste in everyone's mouth after what was otherwise a great win for the Browns.
After careful consideration, I've changed my mind. After Garrett unnecessarily roughed the passer (and a flag was thrown for it), and he got through holding Rudolph on the ground longer than necessary, ripped off his helmet and used it as a weapon to hit Rudolph in the head, he did curl up in a little ball like a coward once he found himself confronted by two offensive lineman. At that point Pouncey shouldn't have tried to hit and kick Garrett, no matter how ineffectual and pathetic the attempt was. Therefore he does deserve the suspension too, because rules are rules.
There is a storied rivalry between the Browns and Steelers so a hard hitting game is expected. However, I'm not the only person who watched the game and came away with the impression that there was a strong resemblance to an old school "bounty" game on the part of the Browns. I wouldn't be surprised if that's how it felt to the players on the field, so Garrett's late hit in the final 8 seconds of a game that was already decided further reinforced that impression. JMO, YMMV