Thor was not being 100% truthful in that scene. He also possessed the Odinpower then. His own power levels were through the roof. That's why Iron Man couldn't do a damn thing to him, and his strikes were devasting.
Without the Odinforce, Thor is about 50% more powerful than Iron Man. With it he's at least 150% more powerful. It makes a big difference.
Care to cite for me where your claim about his power level is justified? Not the part about Odinforce, but the idea that he's only 50% more powerful than Tony w/o it.
I know of no basis to think that Thor was not telling the truth when he said he'd been holding back, and a lot of the events in the Thor books (esp the older ones) back that contention up.
Simply put, Thor is a member of Club Superman, those characters who, if written at their full canon power, are simply too overwhelmingly powerful for most threats they face solo, never mind in team books.