Not entirely true. If some group were to take credit (almost certain to happen), there would be an almost-immediate response, which would bring condemnation from the left for not waiting for Obama to take care of it.
Action against state actors is easy. Action against non-state actors is very difficult.
As to the libs condemnation, Does it really matter what Pres. Bush does, he is going to be condemed by them no matter what he does.