Earlier quoted context omitted.
There are an infinite number of bad ideas in the world. No-one’s life would be improved by hearing them all.
Maybe not. But is one’s life diminished by hearing bad ideas? I don’t think so. For instance, the idea that the Earth is flat is laughable. But my life doesn’t deteriorate nor improve based on that idea. We can all agree it’s a stupid idea, laugh at it, and move on.
Looking at that line of thinking it's ridiculous, there are assumptions and a gross misunderstanding of correlation and causation and confounding factors. But if you are not educated enough to see the problems in those arguments (which I think would be a higher level of education required than believing in flat earth) or if you are a little bit inclined to let someone walk you down a "logical" path of fallacies then it's easy to make that leap. And that's an easy argument for a white nationalist to make. It's a lot less easy for someone to refute it.