I've been a consistent and vocal critic of Hillary Clinton these past couple years, so I think you must be doing something else shady if people are calling you a Nazi.
On the other hand, you can get banned for lots of reasons besides "being a Nazi" or taking part in an "alt-right plot." Sometimes people just don't like talking to other people if it feels like it's hostile or a chore or the other person is just plain annoying. And given they're the arbitrary moderators of a private board, that's their call to make.
That last part seems hard for many to grasp, so to repeat: You were probably not getting banned for being part of some "alt-right conspiracy" or "Nazi plot" (neither of which I mentioned in my post ... weird). You were probably just getting banned because people don't like what you have to say or how you say it.