It would be nice if Russia could explain how the toxin did end up in the 'wrong' hands . . . much the same as weaponry and nuclear material probably goes missing may be a start
I've no idea who would gain an advantage, Governments and 'other' groups move in ways far too complicated for me to understand.
But if I wanted to stab someone to death I'd remove all my fingerprints from the weapon . . . or I wouldn't leave the knife there along with my Tesco loyalty card
Either the Russians are stupid (which I doubt), or they're playing a silly game of bluff bluff double bluff, or they have been stitched up.