And this is the case with any public figure. Any franchise you love, be it Star Wars or Lord of the Rings, or book series, or movie trilogy. Any day news could break about an author, actor, singer, film maker, writer, that suddenly reveals them as being a horrible person. Next thing you know, people are yelling that you are not allowed to enjoy X any more. Ban all of Michael Jacksons music from the radio, in light of the revelations, or you are supporting the pain he caused his victims. No longer show any movies made by Polanski.
I don't like being told what media I'm allowed to like. That doesn't mean I'm not sympathetic to your cause. But you are going to lose a lot of allies by making everyone who likes a thing, out to be a villain.
I'm not a Potter fan. I've only seen the movies, never read the books. If someone wants to run a Potter D&D campaign, let them. And let them have a thread about it on this forum.