I lived and worked in DC when I was just a right leaning libertarian. I worked for government contractors and nonprofits alongside political appointees, elected officials and career bureaucrats. You can hide your power level all you want, but eventually they will catch a whiff of nonconformity. You won’t laugh at the right joke, or maybe you laugh at the wrong joke, but everyone outs themselves in subtle ways and our enemies are hyper vigilant. When this happens you become quietly blacklisted and your career at that organization is effectively dead in the water. I'm not talking about hitler jokes, I was just a right leaning libertarian that didn’t hate white people and that made me an extremist in the beltway.
In the future, nationalists and the adjacents should learn to do what their opponents have done to them in the important institutions and even in the small forums and fandoms. This is the gatekeeping101. Rather than testing them with initiation, I think testing them with group dynamic every now and then is far better way to prevent them to act out of line. There is a place that does subtle gatekeeping pretty well and that is kiwifarms even though I may criticise that place a lot. They don’t treat kindly to autistic spergs in general and doesn’t matter if they have far-left ideology or they are muslim, so most members try to keep in line. Once they have history of sperging out, they get rewarded with pink triangles, a symbol that's more likely to give them lifetime ban. To me that’s the very least we should have done, so we can prevent totally avoidable incidents such as young republican telegram leak next time.
I mean this kind of happens naturally within a group, we don't need to codify it. If someone isn't fitting in you stop inviting them. The problem is trojan horses that tend to suck up to mods pretty early and gain a foothold with one or two that prevent them from being banned.