See, exactly. They're so terrible for any kind of physical activity that clearly no self-respecting ninja would ever wear them. If she could have given the same answer, she would have. She knew he deserved SOME kind of explanation, and she couldn't bring herself to even seriously consider outright lying, but... what, then? What was she supposed to say?

Perhaps the truth, in a broad sense. It may as well have been no answer at all, but at least it could be used as a warning. "...Some things are better left unsaid." That didn't necessarily mean they would stay that way.