> I think people like him might very well help keep disgruntled young men away from the extreme right, by offering a more moderate alternative.

That's probably exactly right. People gather around ideologies that have advocates. They don't look at two extremes and say, "hm, they each have valid points, maybe I'm somewhere between these two", they say, "hm, this one thing side X says is something I really like so they must think most like me. Even though I don't particularly agree with a lot of the rest of what they say, and even if I disagree with side Y less overall, I belong in tribe X".

Moderation/centrism thus also needs advocates if we want a proper balance.