Not just Obama, of course. That is the mantra chanted by evrery progressive whose Manichaean little fantasy worlds consists of their tribe (good) and the other tribe (Bush, conservatives, Nazis, bad bad bad bad). For most of them the rules change when the other tribe is no longer in control although the blame game does not. It isn't universal; there are critics of Obama's policies on his left, particularly with respect to Afghanistan, but these are marginalized and in comparison to his media-amplified acolytes, voiceless.
It is ironic that these are also the voices a principled conservative must defend, ironic in view of the fact that the courtesy is never returned. That may account for part of the steady skewing of public expression toward the left.
An honest man would rescind his criticism of his predecessor over those matters where he finds out that the policies addressing them really are the best choices among bad ones, and adopts them himself. Obama could do that, of course - those criticisms, cheap and ill-founded as they were, worked, and he now resides in the office that they earned him. He won't. It would rob him of his sanctimonious posture. Time will do the same.
Actually Hanson did not specified [Obama] and left it universal, I narrowed it down. For the reason that I wanted to avoid confusion that happens too often when the readers, lets put it charitably - read too fast, and miss sarcasm, or a point that the authors makes on behalf of another party that he deconstructs. So, the fault here is mine.
On the larger point, I agree with you.