It's not just cowardice. It's also strategy. There are many Americans out there who hate Nazis but support fascist beliefs as long as they aren't coming from Nazis. There are many social media moderators out there who will immediately ban self-admitted Nazis but approve of fascist posts and beliefs - this is especially common on modern Reddit where the most important thing is not to scare off advertisers. So Neo-Nazis online learned a long, long time ago to hide their power level, so they can keep posting fascist shit without being banned and gradually radicalize people into agreeing with them.
It's also cowardice, of course. I've found cowards are often authoritarians. They feel more secure with a "big man" backing them. It's why bullies at school attack their targets in gangs and then run to the teacher to cry if the target fights back. And it's also why teachers typically take the bully's side and punish the target for fighting back. Cowardly authoritarians gravitate to careers that give them power over children, and they protect their own.
(Now that I write that, there seems to be a clear parallel with Stonetoss spewing vile shit at minorities for like a decade and running to Elon the minute he faces any personal consequences for his hate. Fascists gonna fash, I guess.)