Her explanation was perfectly reasonable, and it was possible that she hadn't been thinking about his new disability when she'd informed him of it. Perhaps she was only trying to be polite — but even then, was she being polite now because she felt he needed some sort of pity? That a kind word from her might bolster his spirits, or something?

If he hadn't been so self-conscious about the wheelchair, this would have been the end of their interaction — but without the wheelchair this interaction might never have happened in the first place, and that frustrated him to no end. He wanted to prove that he was just as capable as before — to himself more than to her — and so he was hesitant to let it go so easily.

"Interesting," he said, though it obviously didn't interest him in the same way it interested her. "Perhaps I'll get a time-turner and join you, if you don't mind the imposition."