The following is very speculative and should be restated as questions.
Did Russia fear that Pierre Wauthier might be helping the French watch Josef Ackermann at Zurich Insurance Group in 2012 and 2013? Pierre Wauthier had worked for the French government out of university. The French had possibly terminated the Lyapunov Institute because they learned Albert Shiryaev, Freddy Delbaen, Darrell Duffie were meeting in Zurich and were advancing the cause of Russia. Russia would know if that was the reason.
So when Ackermann joined Zurich the French suspected he was there to follow up on this and get files for Russia. They might have had Wauthier try to watch this. Or Ackermann or Russia may have feared it or come to fear it when there was friction between Wauthier and Ackermann.
Ackermann and thus Russia would have gotten Wauthier’s file showing his government employment. That would alert them to this risk. Ackermann may have asked Wauthier about his service with the French government. This type of direction may have brought a response from Wauthier that Ackermann and the Russians interpreted as a threat to them.
This is draft and preliminary. The above is hypotheses and speculation. Comments and corrections welcome. Please restate as questions. All other disclaimers apply.