Your boss spending all their time on a trouble employee means they're also not doing the fifty other things they could to help the team other than bothering you. Yes, managers do have things to do other than bothering their reports. At least good ones do.
While I would love for my boss to purposefully ignore me; it's ok if my boss is only ignoring me because there's no time for me after tending to the other employees. I will not be sad or resentful if my 1:1 had to be canceled because my boss had something else to do.