I agree with you on being interviewed. Bringing someone onto your podcast is more of an implicit endorsement unless you actively push back on their other views. If you don't know about those views, you should have done your research. But, if that was the case, he could have stated it. Imagine that he invited on a vocal flat earther, but discussed gardening with him. In his position, it raises doubts about judgement. If he says, "I didn't realize he was a flat earther--the earth is not flat", he probably keeps his job. But if he threatens to sue people who talk about his appearance on the show, it's a different story.

What concerns me primarily is the guilt by association. You also will see criticism about 'normalising' deviant perspectives merely with the act of engaging in debate (which has some merit, but is applied too generally), which would likely condemn many more. There's no way that can end without people with legitimate points being terrified of speaking.