I've been wondering just how proficient Mikel is in English, and if he misunderstood what the referee was saying...that said, none of his reactions on the pitch with Clattenburg looked like he was reacting to any racial abuse at all. It seems like they had a problem with him during the game and decided to "play the race card" as a means of retaliation.
It's pretty shocking treatment barring Clattenburg from officiating matches when he hasn't been found guilty of any wrongdoing. Let the inquiry do what it does and then take appropriate action. This is a case of presumed guilt before being proven innocent, and it's wrong.