Where are you in Colorado? Hate to be negative, but I doubt one student is going to negatively impact a principal's review, especially when your son is probably one of his/her shining stars.
Here are my arguments to continue funding:
-- Your son has a right to one year's growth in school and if he runs out of HS classes, the logical next step is a college class. What is their plan for dealing with that? And how will that save money?
-- If you can't get college classes through this district, you'll have to investigate offerings in a nearby district (taking your student dollars with you).
Have you checked out any early college high schools? Their whole premise involves college classes, so maybe that would address the issue.
