I didn't say you had to treat the person the same way; you might not like the guy and might not hang out with him. But part of professionalism is being able to work productively with people you strongly disagree with.

I simply don't agree in all circumstances.

Like seven or eight years ago I was at lunch at work with a sister team of ours. They had an intern who decided at lunch to announce that he was a fascist and that gay people were degenerates who were ruining society. Should the team have just said "huh that's quirky" and moved on? What of the gay people on the team who'd now be needing to work with somebody who openly thought that they were filth and expressed this at work?

Now instead of an intern, imagine that this was somebody's boss. Or the CEO. Is it really unprofessional to leave rather than choosing to work for and enrich somebody like that?

I agree with this up to a point. If their shenanigans is making dealing with them even professionally unbearable, you owe it to yourself to determine whether that environment is worth staying in.