I think the problem arises when people want to have it both ways. If you want to say "we don't like you, please leave", you're probably [1] within your rights t

I think the problem arises when people want to have it both ways. If you want to say "we don't like you, please leave", you're probably [1] within your rights to do so, but then you don't also get to claim to have a fair and impartial process. [1] This gets nastier when "you" is something like a corporation, a university, or the well-funded host committee of a generally public event. Legally and ethically, your latitude to exclude people from a private party is much greater than is your latitude to exclude people from a public-ish gathering that any person could show up to.