Actually, he was reportedly directed not to issue a request for more troops. So I don't know if you are correct in that.
And he should question Obama. But it, IMO, does not matter who the POTUS is, a field or theater commander does not publicly question the orders he has been given.
What orders did he question? He was brought in to conduct a counterinsurgency and has been saying the same thing over and over again at his confirmation hearings and ever since. And his positions are entirely consistent with what Obama also said until he went wobbly a few weeks ago and we were left wondering what exactly our strategy is. But "orders"? What orders?
A question we should ask ourselves is how we would have reacted if a General, say Anthony Zinni, had been in active service in Iraq and publicly criticized the surge as unworkable and ineffective. I think we'd have called for his resignation.