Philosophy

For succinctness I'll interpret "stupid" = "immoral and/or false".

This assumes your typical person naturally discards a stupid discourse, once you show it's stupid. I don't think they do; instead they'll discard a discourse that conflicts with their world view, and is not emotionally engaging enough to replace it.

In the light of that, "let the Nazi talk" sounds like a notoriously bad idea. Specially when the Nazi in question are highly rhetorical, i.e. make their stupidity highly emotionally engaging.

A better approach is to address the core claims of the Nazi discourse, in absence of their rhetoric, showing why they're stupid (and cringe). That's basically what a lot of people already do.