Oooh, conspiracy theories. Here's mine.
The governing body of JWs arranged for Mark Sanderson to organize the use of the nerve agent. After losing the court case in Russia and the millions of dollars in real estate, Sanderson & Co decided to get back at Putin by setting him up. Who better to attack then a defector/traitor, or as Sanderson would say 'a mentally diseased human apostate.'
This also sends a message to all current JWs who might be thinking of being unfaithful to the KGB WTS. Further it deflects media attention from the current push for a child abuse investigation into the JWs and WTS in Britain.
As the King of the North and King of the South battle has died down the governing body of JWs have the scriptural advantage of fitting this into their imaginary interpretations of the book of Daniel.
Not to be overlooked is 'the end is near' and 'you can clearly see we are living in the last days' mantra which only encourages JWs to dig deeper into their pockets to donate more and more money.
Evidently the JWs and WTS and their governing body have the most to gain from the attack. Hence they did it.