Marx actually spoke very little about how society and government would function in a Communist society. Most of the philosophy that contributed to the running of socialist states (recall that Communism was a state to be reached after a certain level of development) came much after Marx.

In fact, Marx specifically said that Russia (and countries at similar development levels) weren't ready for Communist revolution. Marx was a determinist. To him, history followed predictable, inescapable patterns. Just as Capitalism was a natural and inevitable reaction to the breakdown of Feudal order, Communism would come due to the internal contradictions of Capitalism. In Marx's view, Russia was still a Feudal state.

Early Russian revolutionaries argued that it would be possible to bypass this step with a government that served as a vanguard - preparing the way for the future Communist state. This would also be the force for "managing" and ruling in the name of the "dictatorship of the proletariat".

Marx didn't say much at all about communism or socialism, he was primarily a theorist of capitalism. He spent all of his time criticizing capitalism instead of talking about how a socialist society would work. One way I guess you could explain USSR censorship from a Marxist perspective (though it probably wasnt the justification or purpose the leaders had) is that marx viewed freedom differently than how we are accustomed to view it. We like to view freedom as in what the laws of the government would allow you/ disallow you to do. Marx thought freedom as a freedom from being dependent on an upper class to give you money so you're not starving and homeless. America may let you say whatever the hell you want to, but in the USSR homelessness and starvation (post WW2) were unheard of.