It’s just about the relative likelihood of the two suggestions.
If there was a Russian spy in the GB I would be incredibly surprised because Russian spies are not common and the GB don’t seem like likely candidates. But I admit it’s not impossible I suppose.
On the other hand, if it turned out there was an abuser in the same group I would not be terribly surprised, simply because abusers are much more common than spies, and the top of religious organisations is precisely where they seem to gravitate. The Australian Royal Commission would seem to suggest congregations on average have had at least one abuser. If the GB is a typical body of elders, with around 50 members over the decades, it’s not at all a farfetched possibility by any means.
None of which is evidence that either scenario is true. Just that one is inherently more likely than the other, and the idea is not accurately described as “crazy”.