"Never" is a big word. Let's extend this to its logical conclusion - imagine a world where every person had a button that would glass the planet. How long would humans last? Seconds? An authoritarian government would be acceptable in comparison to the immediate extinction that would follow.

We've already accepted as a society that some technologies are too big and dangerous for private individuals to have access to, for the sheer pragmatic reason that there are people crazy enough to do literally anything. Technology that allows a single human to kill every other human on Earth is a really good candidate for restriction. Biohacking is such technology. It's real-life nanobots.

I would push back on this framing. Do you consider the FDA or the FCC to be authoritarian? There's a lot of genies they put back in bottles - and while there are some places where people might feel they've infringed on general freedom (the regulation of the content on the airwaves, for example) the fact that our home electronics don't mess with our wifi is something we all take for granted.

Another good example is how you can't photocopy money. Did that stop counterfeiting... no. but it sure did tamp down a lot of casual counterfeiting - and i don't think it actually did harm people's liberty very much.

For the record, I do consider the war on drugs (mentioned by OP) authoritarian. How else can you describe a system of laws that has locked up more people than anyone else?

Furthermore, there is a clear difference between “you can’t do this to other people” and “you can’t do X or Y to your own body”, the latter of which is at play here. Photocopying money, selling dangerous medicine, and spamming the radio waves with noise actually affects other people. Personal experimentation with mRNA does not.

Regulating mass market mRNA products before they can be sold? Sure. Banning individual experimentation? Hell no.

For an interesting take on this, find and read the Isaac Asimov short story "The Dead Past".