I don't see a problem/retcon. His being called "weak tk" just means that it takes a huge effort for him to muster enough of it to have a "strong" effect, like he did against Nimrod, and it'd probably be too draining for him to use it to fly. He's always focused on his TP, so his TK likely isn't reliable for combat/defense, anyway, but I wouldn't mind if he's shown to have been practicing it to change that.