i was thinking about an NPC or even a very atypical BBEG at first, but if you can roleplay a surly loyal evil librarian, it would be even better!
also, something about seeing written "offensive text" made me think:
PC:"i reveal the newsletter of [insert hate-group]"
DM:"aaaand the monster takes d8 dmg"
it could also be interpreted as swatting someone with a newspaper