Fellow Trump supporter here. You wrote that you are a "paid intern." I hate to be the one to tell you, but that is pretty low in the coporate food chain, corporate prison gang system, or coporate organized crime family or whatever similar analogy you would like. You need to accept this or either leave and start a new job or a new business where you get to set the culture. Yes, HR more than likely lied to you about dealing with this. You are a paid intern who is leaving in a few weeks and he is the boss. Unless your boss did something really bad to you, HR isn't going to get involved just because your boss badmouthed Trump. Just be quiet, do your job well, get all the experience you can, get paid and move on to become bigger and better.