SlippyMagnus's avatar
Ask him what he was referring to. By closing his range of options down on what you actually want to hear (constructive criticism) then he'll either make more stupid comments, or he'll be hemmed into doing what you want.

Ask him what he would have liked to see, then let them know how you worked their ideas into the picture anyways.
They'll feel stupid, and either leave or make more stupid comments.

At this point, if they've been stupid the whole time, you just need to block them and Hide their comments.