Asking which kind of politicians you vote for is pretty obviously about discriminating. But I'm not surprised that this is happening in health care because that

Asking which kind of politicians you vote for is pretty obviously about discriminating. But I'm not surprised that this is happening in health care because that space is highly politicized in the US and strong right wingers are likely to have moral objections to several medical procedures. Strong left wingers are likely to have moral objections to the American medical system's notoriously ruthless business practices. In other words, they probably want people who don't have particularly strong political views. Sadly, political affiliation and political belief are not protected classes under US civil rights law so employers can legally discriminate on this basis. This is actually a big part of why the American political system is so dominated by corporate interests because many people are terrified of hurting their career prospects if they participate in the political process.