It's not like they can just pour the vial into a big vat, let if ferment, and then pour that stuff into missile warheads.... making weaponized botulism toxin may be easier than making a nuclear warhead, but it's still not a simple task.

The capability to disperse microbes and toxins over a wide area as an inhalable aerosol – the form best suited for inflicting mass casualties – requires a delivery system whose development would outstrip the technical capabilities of all but the most sophisticated terrorists. Not only is the dissemination process for biological agents inherently complex, requiring specialized equipment and expertise, but effective dispersal is easily disrupted by environmental and meteorological conditions.

It's certainly not a good thing that this scientist was hiding a vial of the stuff, but it's a long ways from justifying an invasion.