The problem with relying on any type of internal resistance is sorting out the real ones from the intelligence folks -- and many of the loudest ones are agents provocateurs. We don't have time to engage is such a time-consuming endeavor -- Iran will very soon have the bomb, and even if there were a significant real resistance, counting on it alone would be unwise. Rebellions are uncertain endeavors, at best, and we just don't have time to see how one might play out in Iran.
Successful popular uprisings are mostly fantasy anyway.