The question of 'weapons grade' has to do with the quality of its refinement.
The Soviets typically created liquid anthrax; easier to store and deal with.
The more deadly anthrax is dried which involves sophisticated dessicators and centrifuges; the Iraqis are known (by our friend Scott Ritter) to possess this quality of machinery.
I defy him to show any civilian group in the US is capable of such manufacture.
I also defy him to show any proof or even believable speculation that any domestic group is willing or capable of doing this.
It's irresponsible - at the least- of him to be mouthing such tripe.