The same way I define if someone is gay, christian, or whatever other personal label, I ask them. If that's not an option, I'm not going to make a judgement based on random shit.
This guy was a complicated person who doesn't seem to strongly identify with either party, obviously Hannity is full of shit, but that doesn't mean we should lose sight of nuance in our reality.
Living in a deep red state, it's the only chance I have to cast a vote that matters. Not just the presidency, but most of our state and local politicians are decided in the Republican primary. Half the positions I'm talking about literally run unopposed in the general election. So I'm going to keep voting for the lesser evil and doing what I can where I live.