NO! If this is working for your son, the principal is giving you hair-brained excuses. I'm a teacher as well.
We accelerated my son by only a grade level as a starting point this year. It was a slow process because our principal wanted clear-cut data and a process laid out that would support our decision (I feared appearing like I was being accommodated because I teach there as well) so that when others asked for the same, a process was in place.
I would suggest keeping the conversation alive. I can share our district process for acceleration with you if you'd like. (I don't have the flow chart handy at home, but can scan and e-mail it later.) PUSH PUSH PUSH . . . not only for your son, but for every kid who deserves this!!!
