Yes, yelling at and taunting someone who makes a 7 figure income is certainly cause for removal.
New York fans have a horrible reputation of being brutal, but I have to say I've seen many drunken and/or profane fans thrown out by security. Heck, I even saw security come over at Yankee Stadium and get ready to throw out a Yankee fan who was trash-talking Mets fans! The only reason the guy didn't get thrown out is because the Mets fans told security to let the guy stay.
Anyhow, it sounds like this Oakland jerk has been a problem all season for opposing pitchers. Oaktown security should have put a stop to him a long time ago.