Well, I think the USSR wasn't portrayed as a real communist nation. For an instance it is implied that money was never eliminated.
Else I feel the comic book greatly implied that communism had become hindering to human individual development by "repressing human resourcefulness".
It is also implied that humanity had to some extent become terriby dependant on Superman and that the whole Soviet economic system, inspite of having thrived for decades and greatly evolved after all was completely dependant on Superman, something I consider imposible.
The book starts becoming very bizarre by the end...