I think it's even more dangerous to say that there are no universal moral values at all, and "oh, so what if they are killing/torturing/raping people and mistreating, oppressing and enslaving parts of the population? It's their culture!" Which is really a thinly veiled "meh, they're barbarians, who cares what they do to each other!", hypocritically dressed up as "respect for other cultures" when it's really the opposite.
I agree. Things like that are not just wrong because you don't like them...they are objectively
wrong, unlike frivolous things like what color or flavor is best. And maybe it's just me, but there's a point when if things become bad enough, and all efforts to politely explain why a behavior makes me uncomfortable fail, yet the person keeps doing it, I would rather cut ties than be associated with or a party to that behavior in any way. If a polite (but firm) request to stop the given immoral and unethical behavior fails, I do not want it to look to that person or to anyone as though I were lending support to an abuser. Sending that kind of message--being willing to take a stand--encourages others to do so as well. Someone has to be bold enough to take that first step. It shouldn't come with an assault or even unkind words, but there is no problem with factually stating (for instance) that one cannot associate with an abuser or denigrater of women (or any other person who might be abused by the individual in question).
When you look at what the Federation as whole does, they are party to a LOT of abusive behavior, by failing to call their member and allied states on it. One of the most egregious examples is with the Klingons. By maintaining a tight alliance and trade relation with the Klingons (and not a mere non-aggression pact, which simply means they won't shoot each other), they are in effect endorsing Klingon conquests and brutality, which has continued
even while the Klingons are allied with the Federation. Yet they dare to rail on about the same things when talking to other powers. If they mean it, then they shouldn't endorse it when the Klingons do it either. They really ought not be associating with the Klingons any more than it takes to prevent a war from breaking out.