Personally I am increasingly uncomfortable feeling the “need” to apologize to regressive people about feeling hurt or insulted. They are entirely responsible for their actions.

The "I'm so sorry your feelings are hurt" non-apology is always an option. It sounds like an apology, but it basically means "I'm sorry you suck" rather than apologising for doing something wrong. In most contexts, it's an asshole thing to do because it's a refusal to acknowledge that someone has a good reason to be hurt. When dealing with bigots, "I'm sorry you suck" is perhaps the most appropriate response.