Earlier quoted context omitted.
It's not really a fine line. There are specific, protected people-features you can't use to discriminate. Saying stupid shit isn't one of them. Race is. Those laws don't exist because we don't agree with their reasons. They exist to protect people who have been categorically repressed for hundreds of years.
This brings an interesting workaround to mind. What if they register their ideology as a religion? Iirc it is a protected class in US so they cannot be banned due to it. However people getting banned like this rarely are inventive enough to figure out ways to fight back.
The thing about the law is that it doesn't operate like code. You can't just cast(ideology) and expect it to work within the framework of law, because the law is (luckily) interpreted by people who expect it to be taken advantage of by the unscrupulous.
Otherwise, literally every corporation would already have registered themselves as a religion just to avoid paying taxes.