Definitely a no-no. Glad you walked in before he figured it out.
If mine had 'activated' it, it would have become his personal cutter - after an explosive tirade from me. Wouldn't happen because yellow-headed quilting pins mysteriously showed up in his workshop five years ago. That upset me enough to impress him not to borrow again.
I would have looked on it as an opportunity to go shopping for another cutter.