You're giving him way too much credit. If there's widespread lead poisoning that's causing cognitive decline for millions of people, there will be communists among those millions of people. To think otherwise is wrong for 2 huge reasons:

1. You're essentializing right wing ideology to the point that it's impossible to think the people who believe in it could ever change, because based on this worldview the only people who believe in right wing ideology are biologically inferior.
2. You're making the in-group (communists in this case) think that they're inherently superior to those who have something wrong with them at a biological level.

It goes without saying that leftists need to believe that change is possible; that doesn't mean being naive about how hard that's gonna be for American fascists, or even to believe that redeeming every single one of them is necessary. But you at least need to believe that there's nothing that's baked into reactionaries that makes them reactionary, or else you're halfway to accepting an aristocratic and austere worldview where you set out to give comfort only to the sensitive and noble people, and nothing but hard labor to the brutes. In other words, you may as well drop Marx and pick up Nietzsche.