None of this stuff...
...is a smoking gun that justifies a pre-emptive war. Its merely evidence of wishful thinking on the part of a petty dictator that someday he might restart his chemical and biological weapons programs. His rather inept efforts to hide his interest in this is only evidence that the inspections and sanctions were working.
As for botulinum toxin, it may very very dangerous stuff, but its not exactly a readily deployable bio-weapon. And, frankly we have more to fear from someone with bad intentions right here in the United States manufacturing the stuff in their own garage.