Bingo.
He probably thinks it is 50/50 that it will collapse on its own.
He also thinks he could be the "unification" choice by having lived in the USA, being the Shah's kid (and descendant of Mohammed, the false prophet), yet against the attack.
Basically ride in on a white horse, saying "not my fault."
The first person or group that "rides in" will have to spill so much Mullah blood that it will come back to bite them politically later on and the Monarchy cannot afford the taint.
Read Operation Sandblast on http://www.antimullah.com for a better feel of the two phase regime change that would make sense, though some revisions are equired as the article was written some months ago.