I think it was maybe the agression he was showing while saying it - there was one point in his tirade where it actuall looked like her spat - not saying AT anyone or anything, just saying it looked like he spat - so I imagine the red was for his aggressiveness. The moron has no-one to blame but himslef, to be honest - an experienced player should know better than that. It's the behaviour you expect from youngsters, to be honest.
As for the penalty, he caught the boy (who was already losing balance). A stupid, stupid challenge in the box on a player heading away from goal and looking unlikely to retain posession. Rangers/Bougherra can have no complaints about the whole situation.