Indeed. Though don't under estimate the creative thinking barrier - ie people don't do the possible because it never occurred to them - a lack of imagination.

Hence copy cat kind of attacks - I mean why focus on all this complicated stuff with explosives etc when you can just fly a plane into a building or a car through a crowd.

Obviously due to the self replicating nature of biologics weapons - just one instance could be catastrophic - but the only real barrier is the hope that the Venn diagram of people who might want to do it doesn't overlap with the people with the get up and go to actually make it happen. Don't see having the knowledge as a additional filter - as if you have the get up and go - as you say, you can acquire the knowledge LLM or not.