Earlier quoted context omitted.
I ask, if that person is truly unpleasant have you spoken to them about how unpleasant they are? Not to defend but how is someone to recognise a fault of their own if they're not called upon? Unless its truly terrible and they know they are doing it on purpose. The issue we live in nowadays we are all scared how to tell each other how we feel towards and that we now safe harbour them by throwing them a label and appr…
Sometimes, yes, we talk to them. But I'm a DM, not their therapist or their dad - I'm not obligated to hand-hold someone through a radical restructuring of their personality. And, it might not surprise you to find out, some people react very badly to being criticized. And I'm not particularly interested in having an argument over my subjective opinion of a person. I just don't want to be around them anymore.
"No that's not alright, cut the crap otherwise your out of here"
Why play with them and not just cut them out completely? By keeping them in group your only enforcing their unpleasantness.