Why is this statement assumed to be true? It is far from clear that advanced weapons in the hands of irresponsible, impulsive and ideological individuals cannot cause large scale chaos.
To build an egg requires the effort on the level of states or corporations but to break it requires just an individual motivated to do so.
With closed models and research only well funded entities participate (state actors and large corps).
If you want to draw parallels with advanced weapons, the difference is that weapon is also an antidote to itself.
Compare nukes. You can't stop a bad nuke with a good nuke. If I give you a nuke, the probability that you get nuked only goes up.
Afaict, nobody has even offered any explanation how open weights do anything to defend you from bad actors with LLMs.
So far, that's exactly what we've done. MAD works. Ask the Ukrainians -- or what's left of them -- what happens when you voluntarily disarm.
There maybe good reasons to have open models but pretending that systems that allow an individual to project power beyond their immediate vicinity is harmless is naive.
An individual with a weapon can almost always cause carnage at a level greater than their own with before any first responder can deal with it. Be that a viral video of someone faked to be blaspheming or somebody with a weapon in a school. Once the shooting starts it takes phenomenal energy to put the problem back in the box.