Do you think that gods are less powerful than politicians? Good intentions and unlimited power are not always a good combination. I would trust Harry with literal omnipotence more than most people, but he's far too arrogant to be trusted with enormous-but-not-unlimited power, of the sort where he can screw things up better than he can fix them.

I'm not sure I'd even trust him with omnipotence, since presumably even an omnipotent agent is still bound by the laws of logic and mathematics. In any case omnipotence without omniscience, at least, strikes me as recipe for disaster.