Not having to deal with such people will make lots of people very happy, and them in the long run happy as well.
So the positive utility outweighs the negative utility of the punishment, which is at least plausible, and makes sense under standard forms of utilitarianism. But if their utility function really should be counted negatively, this would just be an incidental fact.
This still doesn't change the fact that hearing about Mr. Rich Misogynist here enjoying a 7-figure trust fund, mistreating women, and generally being happy at the expense of others makes me generally unhappy, indicating a negative term for his happiness in my utility function.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.