I'd be interested in hearing a lawyer's take, I could see it going either way. I bet it depends on the state tbh

I would classify it as biological warfare, but at least they provided full disclosure regarding the dangerous defects.

What kind of casual Facebook marketplace person would want this? Someone with nefarious intentions?

"Mwah-ah-ah I can feed this to my neighbor's dog who barks all day. This will make him quiet."

It might matter that it's possibly not transmissible to humans? I'm not sure.