I am not saying he can't be hurt by energy, he could feel the initial hit ,but once his own powers kick in he could manipulate it not to hurt him.Anyway this is an attempt to explain something not only fictitious but also with no real frame of reference, I'm trying to 'get it' in a specific way to keep the upper limit an actual limit.On the one hand he is an omega of energy manipulation which presupposes enough dexterity and finesse to fine tune the energy in specific ways which requires willpower ,on the other hand lack of willpower refers to him just having unbridled energy discharge which could also have no upper limit.I guess writers want to have it both ways when they use such nebulous terms.