In which case, silencing them makes them martyrs and makes them feel important, which generally never works. People love being members of a secret "in-group" -

In which case, silencing them makes them martyrs and makes them feel important, which generally never works. People love being members of a secret "in-group" - just look at cults. Plus, it's not like it won't stop them - after all, the original Nazis did not need social media, or the internet, to obtain power. I say bring it out in daylight, and let them loose every debate they have so they look like idiots instead of martyrs.