Mixed feelings on this, but when someone accepts racist arguments and repeats them uncritically…what are you supposed to call them?

Well, prejudiced or racist always work.

Maybe I'm using the term wrong, but I always thought of fascism as specifically when a government (or group) carries out a campaign of suffering and death on a civilian population. So, when Trump talks about mass deportations, I'd consider that fascist (although I'm skeptical there's really the will, let alone the capacity, to actually attempt it). When he talks about Making America Great Again, that's just reactionary talk - it was better in the past, so we are re-enacting the past. Fascism often has reactionary elements, and reaction can be used to justify fascist actions, but they don't always show up together.