It's - where should he start - so she might have noticed that Crafters have trouble touching each other, or touching each others' things, or being in each others' spaces? That's most obvious with things that are clearly another person's, but it affects anything that isn't clearly theirs, to a lesser degree. He's noticeably less able to take actions here than he is in his own territory, because it isn't his, it's a shared space. And it doesn't matter if everyone agrees that it's fine for him to, say, use the spare dishes in that one cabinet; the problem is in him, in what he feels is possible or impossible for him to do.
And that sense of 'this is my territory, I'm allowed to do anything I want here' isn't unbreakable, either. It doesn't come up often, because Crafters have such a strong taboo on taking actions in others' territories that aren't clearly welcome, but when it does come up - if there's a miscommunication, or an accident, or something like that - that'll damage that Crafter's sense of ownership of the space, often temporarily but possibly permanently, with the same kind of effect. Unwanted touch does the same thing with even more dramatic results; not feeling that you have full ownership of your body is really bad.
And that's what'll happen if she takes action in Crafters' territories without their permission. Worse than usual, even, since usually it's an accident and the person who made the mistake can say that, and she'd be doing it on purpose. He expects that for a fair number of Crafters even knowing that she could take action in their territories at any time and there's nothing they could do about it would be enough to cause major problems, and so would knowing that she's watching them closely enough to notice them asking her to. And the usual thing to do when there's a really catastrophic loss of felt sense of one's territory is one's own is to move, but if her thing is everywhere... he'd expect a lot of people to die of not being able to feed themselves or do other basic self-care like that. It'd be really bad.