I would phrase it as there were a handful of political topics that couldn't be discussed as freely as in the west in USSR. In many ways there was a lot more freedom of speech. Here's a great example of that from an interview with George Lucas where he explains how film makers in USSR had far more freedom than those under capitalist regimes.

I would also argue that freedom of speech is only meaningful when that speech can translate into tangible action. What the west has is the freedom to scream into the void, but as soon as there is any potential threat to the state then it's quickly dismantled. Great examples of that are the Black Panthers and MLK movement.

Finally, I think that every society has restrictions on freedom of speech, and some such restrictions are obviously desirable. I fully support restrictions on capitalist propaganda and right wing extremism.

However, my point was not to argue against freedom of speech but rather that the society should focus on ensuring that the basic needs are met and that regular people can live comfortable lives before focusing on maximizing freedom of speech. It's a question of priorities.

And given that counter revolutionary elements exist in socialist societies who try to undermine socialism and bring back capitalism, suppressing this sort of speech is justified. If you look at USSR, what ultimately facilitated a counter revolution was the liberalization under glasnost and perestroyka programs that Gorbachev introduced.