That's not really what fascism means or what groupthink means.
Fascism requires belief in marshaling the power of the state behind a supreme leader in hopes of advancing a narrowly defined nationalist agenda. Groupthink is an internal psychological condition that's indicated by clustering around ideas and not being able to accept rational ones as valid.
If these people could somehow accomplish exactly that then they probably would. I have little doubt that many of them would be more than happy to topple American democracy if they could and establish a new authoritarian regime in its place.
My point, as should be clear, is that they have a viewpoint and believe they are justified in doing whatever is necessary to achieve their goals, giving no thought or concern to the rights of others who think and believe differently. They believe this is okay because they are morally justified by being "right."
I am reminded of the documentary The Weather Underground--one of my favorite docs of all time BTW--and one of the former Weathermen recounts his time in the group and says, "When you believe you have right on your side you can do some pretty horrific things."
So much fucked up shit has happened in the world because people got suffused with a sense of righteousness because they became convinced that they were the good and moral ones and those who disagreed with them were evil and needed to be stopped at all costs.
Are you saying the groups Antifa protests (typically white nationalists) are propounding a rational view?
I take a lot of issue with white nationalists because I think their philosophy is thoroughly un-American.
Even beyond all the racial stuff, their political philosophy is incompatible with American values. Richard Spencer, for instance, I know has said that he's not a fan of democracy and that his proposed white ethno-state would espouse socialism. Quite literally Nazi shit.
But regardless of how I feel about it, I still respect their right to think, believe and say whatever they want. The first amendment, after all, was not put in place to protect popular speech, but rather to protect unpopular speech. I think that fringe voices challenge our dedication to free thought and free speech, so if you decide that these people need to be silenced then you failed the test.