I think when most people talk about a bioweapon to be concerned about they mean something that can be deployed against a large number of people.

IDK much about Botox as a weapon, but can you use it to deploy broadly? With ricin, that's just another poison, so how's that better than rat poison?

It is more just that there are a wide variety of existing ways available to harm or kill the population. No need to invoke the specter that AI magic is going to engineer some super bug. Plenty of virulent pathogens already around.

You could trivially cause enormous harm by sabotaging electrical distribution, water treatment, hospitals, airports, etc. Go to any food manufacturer/distributor and contaminate the products with listeria or such.

You can get PTFE spray in any hardware store.