They should be allowed to express their opinion until it becomes tangible and problematic for said outgroup?

Yes. Exactly. That is the fundamental basis of a free society and the legal system. The line is drawn at tangible actions and imminent threats.

Wow, imagine being the person arguing that groups like the Nazis should be allowed into power and killing others before it’s time to fight back.

“Ah yes, let’s let these people who want to kill and exterminate others lie their way into being able to control all the resources of the government and of course the military before we try to fight back”.

You’re either a massive idiot useful to such people at best, or you’re arguing in bad faith hoping you’ll be in the in-group so you can kill those you hate on uneven ground as a coward at worst.