I think the Unabomber must be the index case for this sort of thing, a loner who did resort to terrorism, but the ideology in his manifesto was not particularly unusual, like a lot of people believe similar things but never blow anybody up. He was a smart guy but it took him decades to build the skills to construct bombs that could kill people reliably. I am more than a little skeptical that a nobody could make a world-killing virus with AI but if you were concerned about that you'd like to see the mRNA vaccine machine revved up and ready to go in any emergency and look for ways to preempt the political reaction that we'd expect if there was another pandemic. (e.g. the breakdown of trust is more dangerous than the disease!)