I wonder if it was a double fakeout. Stuff the ballot box in a non-obvious way for Author A and then stuff it in an obvious way for Author B. They see B's fake votes and remove them, but don't notice that A's was at all fake and accept them.

such an elaborate conspiracy could never be realized

Is it elaborate? Such a fake out is a trope of basic game theory that would be easy to see for someone who understands basic data analysis. And the implementation would be trivial compared to the work the malicious actor has already gone through to sponsor the memberships.