Kim,
I can only say that I know emotion can play a big role in TS and I found things got worse with a divorce. But there was more to it at the biological level. Also, if we had tried counseling etc. only for it we would really have missed the boat. Plus once we figured out there were environmental things going on, it seemed to make him feel better about himself--like it wasn't all in his mind. What have you tried so far for him, if you do believe it is trauma? Maybe someone trained in emotional release tecniques could help?
Since you say his dad had tics, that would point to a biological connection wouldn't it? If I were you I would look at it from all angles so not to miss anything! when we tell a child it is emotional/anxiety they may read this as its something they should be albe to control? What do you know about the school, is it old and moldy or new and toxic? any idea?
theres so much to explore it can make you dizzy. don't close any doors, that's all i would suggest. If he's ten, maybe he can start telling you what things besides social stuff makes him tic more. like foods etc. Worth a try! Ziam