If some unhinged psycho want to build nerve agents and bombs I think it's laughable to believe an LLM will be the tool that makes a difference in enabling them to do so.
As you said the information is already out there - getting info on how to do this stuff is not the barrier you think it is.
> I think it's laughable to believe an LLM will be the tool that makes a difference
If you think it's "laughable", what do you think tools are for? Every tool makes some difference, that's why they get used.
The better models are already at the level of a (free) everything-intern, and it's very easy to use them for high-level control of robotics.
> getting info on how to do this stuff is not the barrier you think it is.
Knowing what question you need to ask in order to not kill oneself in the process, however, is.
Secondary school chemistry lessons taught me two distinct ways to make chlorine using only things found in a normal kitchen; but the were taught in the context "don't do X or Y, that makes chlorine", not "here's some PPE, let's get to work".
As you said the information is already out there - getting info on how to do this stuff is not the barrier you think it is.