I have no problem with this being done to Kevin (I personally find Kevin getting doorbelled pretty funny) but this is still what I assume is not supposed to happen.

From what I can tell, the steps are:

1: grab a critter and have them sit in the library

2: cast doorbell on them and run out before placing it down

3: annoy the critter inside despite the fact that you're probably not supposed to be allowed to do this to a critter in the library since sigils/pickpocketing also aren't allowed in there.