He's not high stepping. He's not celebrating. He hasn't made a sack. He hasn't even made the tackle. The play is to the other side of the field. He's not pushed and he's not off balance. His appeal was based on him being punished too harshly - and considering what other players have done in the past he's got a point.
He's admitted that he stepped on the player. If you're saying that he knew someone was there, well then it's hard to claim that it's unintentional. Sheesh! There are even Seahawks fans here who think it was dirty.