I have recently been made aware of the belief held by some that Gagarin was only the first man to survive and return from space flight. Supposedly, there were a few others, before and after, who
--died on re-entry,
--failed to reenter and died in orbit,
--accelerated a little too hard and went into interplanetary space without the means to return.
Given the Soviet penchant for secrecy-- Gagarin's flight wasn't made public until it was over, IIRC-- I shouldn't be surprised.
All this to say that perhaps the cosmonauts in the OP were possibly "removed" for other than ideological reasons-- perhaps to avoid questions like "who is that guy, did he fly, why hasn't he been seen since 1962" etc.