Also, your own real-life examples show how "Anything that can kill other people can also kill you" has failed to stop people from tinkering with dangerous viruses! I'm not sure if you intend for these examples to be reassuring, but I'm not reassured.
> A lot of the people talking about bioweapons of doom are saying that standard graduate level knowledge is an existential risk to humanity.
The stronger version of the argument is: an insufficiently-aligned AI (which, being non-biological, is immune to viruses) having standard graduate level bio knowledge _plus_ the ability to operate a wet lab via tool calls (coming very soon if not here already!) adds up to existential risk to humanity.
You don't even need a maximally-automated lab if humans are willing to tele-operate equipment at the agent's direction, and those humans don't need to fully understand what's going on.