That's like saying we shouldn't deal with neo-nazis who aren't in power. They're choosing to side with evil and thus deserve equal punishment. "Oh no they might feel bad about it" good they should feel bad. They should genuinely feel bad.
Trump getting elected will cause a legitimacy crisis. You have someone openly criminal (as opposed to the rest which were covert about it) flagrantly breaking the rules, which is the one thing all “great” societies did milliseconds before collapsing, and he will be elected in through the very system itself because 1) the institutions failed to prevent him from running and 2) He was running against a corpse with record low approval literally currently complicit in and funding an active ongoing genocide.
It’s not going to be long before people start asking questions and noticing that the entire fucking system has been rotten the entire time.