It's not my job to make the argument for them.
For what it's worth, I have done your suggested exercise, and I find every causal link (including the ones brought up by luminaries like Amodei) to be outrageous and poorly argued. But it's not my job expend effort to make their outrageous arguments better.
If we have a bioweapon close call, would you consider AI an existential risk at that point? If not, how close would we need to get?
You don't need to answer here, or disclose anything publicly - just think and remember.
I think your viewpoint is totally valid, and I'm not trying to argue against it.
The substantive difference is that you're asking me to dream up ridiculously improbable scenarios, which is probably the actual point. Just like "The End is Near Accept Jesus" guy on the street corner gets what he wants as soon as I engage.
To quote a famous movie about doomy AI scenarios: "the only winning move is not to play."
The thing is, this doesn't really mean anything.
What is a bioweapon close call? What is the process in which a bioweapon close call happens? An AI that hacks all cell phones to emitt anthrax?
I'm not asking you to post it here, I'm asking you to think about it and then remember it in the future, should the event ever occur.