Regardless of whether you think it's a good idea or not, restricting access to guns and free speech is an authoritarian play: it's using the authority of the State to restrict certain liberties in the intent of doing good.
Saying 'this law is not authoritarian' is always a contradiction.
That's called civilisation.
And the US doesn't have absolute free speech. It never did.
Just like other democracies, it has restrictions on speech for various reasons, some good and some bad. It's about where an individual country draws their line on the spectrum:
https://en.wikipedia.org/wiki/United_States_free_speech_exce...
Some US states have obscenity laws that other developed democracies don't. Obscenity laws. Just think about how insane that is as a concept.
As to the USA.. Well, I think it's important to consider that the USA is about 68 times the population of NZ. 68 New Zealands, think about that. Some of those New Zealands are quite safe even relative to other countries, and others are not. Firearm homicide rates, along with other crime rates, fluctuate wildly by region. And yet all those regions have the 1st and 2nd amendment.
IMHO, as a NZ resident, NZ is definitely safer and nicer than the bad parts of the US. However, I do not believe it has too much to do with its loose free speech protections and firearm restrictions. New Zealand is probably sturdy enough to have stronger free speech and personal liberty protections while being as safe or safer as the safest regions in the USA..