It's hardly hardcore communist propaganda. It's some of his best work. It is anticapitalist propaganda, for sure, but hardly hardcore communist propaganda, and is very prescient of many issues (well, hard to be prescient about something that was always the case).
Moreover, Dunno on the Moon uses concepts and ideas that a person in the USSR would have no to little idea about (e.g. stock markets, negative campaigning etc.), or concepts that didn't even exist at the time of writing (police batons with built-in electric discharges first appeared in the West after Nosov's death).
If you just show worst bits of one side, make them define the side as a whole, and then show idealized version of the other side, that is pretty much propaganda, even if these worst bits are described accurately.
Moreover, Dunno on the Moon uses concepts and ideas that a person in the USSR would have no to little idea about (e.g. stock markets, negative campaigning etc.), or concepts that didn't even exist at the time of writing (police batons with built-in electric discharges first appeared in the West after Nosov's death).