Yep, you can't put the genie back in the bottle.

If you successfully tested a nuclear weapon it would be incredibly naive to think you could save the world from nuclear weapons just by keeping its implementation secret, someone else out there is just as smart as you and once you've proven it's possible then it's just a matter of time before someone else figures out how you did it.

Although personally I don't think their creation is anywhere near as dangerous as they would like to think, feels more like a PR stunt/dystopia LARPing.

Yes, indeed, I myself have several large nuclear weapons at home which completely validates your point.

There is always that boy who built a nuclear reactor at home. Not quite having nukes besides the wine bottles in the cellar but he overcame at least some of the problems you'd face to get there, that shouldn't be doable

https://en.m.wikipedia.org/wiki/David_Hahn