Some opinions are unacceptable though.
I don't think anyone is duty bound to listen to racist statements.
I think it's important not to promote this kind of false equivalency, where everyone's opinions are equally valid and should be listened to and respected. Statements that are racist, homophobic, bigoted, misogynist, etc., do not deserve respect.
Now obviously, people may differ on whether statements are racist or not. If someone comes back to me and says, 'But I don't think I'm being racist', then yes I would engage with them and explain why I think it is actually racist.
I honestly don't think, in most cases, people say something is racist in order to shut people up. They say something is racist because they genuinely believe it is offensive.
The main problem, it seems to me, is that many white people not just in Britain but everywhere have very outdated views on what racism is.