That doesn’t solve the brand reputation problem. Some users don’t want to be on a site that has anything to do with controversial / unsavory content. Bars have a right to refuse service to anyone for any reason not protected by law (race, etc.). Social media is the online equivalent of the watering hole; should not they be afforded the same right?

No.

If people don't want to be on a site with someone, even if they don't have to interact with them, then that's just too bad. I will always favor local, positive rights over global, negative rights.

The right to > The right for somebody else to not.

I'm a value utilitarian. I think society should be organized so that humans can follow their interests. As such, I believe it is counterproductive for people to have an interest in others not following their interests; that's an interest that reduces net interest satisfaction rather than raises it.