The only solution is for people to stop seeing criticism of Democrats as endorsement for Republicans
Did you know there are mathematicians who study fairness and bias in voting systems? Well, is possible for you to convince those mathematicians of that fact, but first you'll have to abolish First Past The Post and replace it with a condorcet method.
Now I'm not using that as a gotcha. I think changing America's voting system is a great idea. But it's also really hard. So I'll support you in trying to do that. But if you want to change people's understanding of the system without changing the system, I don't think that's a serious ask, because these people you're criticising tend to have a good understanding of the mathematics.