Yeah, but it's my experience those people are usually already pretty galvanized. And those are the sorts of asshats whose opinions are not going to be changed or educated in any event.
It's the unaware and indifferent that need to be inoculated against repugnant things like these jerks spew, and the only way to inoculate is through exposure. Let these assholes have their say (so long as all they do is talk), but make damn sure someone reasonable and intelligent is also present to point out how vile what they are saying is.
tl;dr: Fight their speech with more free speech. Only use calm, convincing, reasonable speech. After all, it's not hard to pick holes in these idiot's arguments. Trying to censor these assholes only adds weight to their drivel and makes them look like victims.
☝ This. So much this. As amusing as the gorilla guy and banana guy were, they aren't really accomplishing much either, other than attracting attention to these fucktards.