[@Regitnui]
He interacts with such a being as if they really were a humanoid. That is to say, he could walk 'into' her shell and hold her now maybe non-existant hand. In the same way that he could beat a super-strong Epic in an arm-wrestling competition or walk through a barrage of magical lasers like they weren't there.

Also, it's not just negation. A flying super would not drop out of the sky, they would already be on the ground as if they never had the power to fly in the first place. Nobody would get portal-cut, because they'd either be here or they'd have never left their destination in the first place.

I hadn't considered the large-scale ramifications of his power, I admit. I just liked the idea of a grumpy old man shouting at people for thinking superpowers were real, and nobody being able to refute him because of his weird power. So I'm not arguing that your rejection was not justified, it was. Just that it's a shame, because I liked the character concept.