I think everyone has the right to express their opinion on anything whether they're part of the culture or not, whether they're informed or not, etc. It's the reader's choice how much value they give to that opinion according to their standards (everyone's own personal standard's are valid). The "you can't have an opinion on this because you're not X or Y" is a lazy way to disregard a possibly (or not) ignorant opinion instead of giving the proper arguments to refute it. A lot of people will say that it's not their job to educate or explain or whatever and that's 100% true, you absolutely don't have to do that if you don't want to. But people are still allowed to give their opinion, and others are allowed to disagree and get angry, specially when the person is being wilfully ignorant and hateful. I do think some ideas should not have a platform to be spread but that's a more complex topic.