I'm not sure what you're getting at. Universally, modern militaries don't like journalists wandering around near their assets.
> and Russia enforced press restrictions across all of Ukrainian territory
Your analogy isn't very different from reality. Russia does enforce press restrictions near military assets, including in occupied parts of Ukraine.
> However, in this theoretical USSR, Ukrainians did not get Soviet citizenship, and were under a total blockade.
That would seem very unfair, if Russia did it just because they're mean and not because this hypothetical Ukraine had launched tens of thousands of rockets at them. But I'm not sure what it has to do with press restrictions.
> even during “ceasefire” periods
The ceasefire was pretty much dead once Hamas attacked IDF soldiers in Rafah. Now it's just a lower-intensity conflict. Still not a great idea to have random journalists waltzing around and tweeting photos of military assets.
> it simply wants a media blackout
This is a funny explanation because there are millions of cameras in Gaza anyway, and this is the second most covered conflict (by metrics like article count) in all of human history. Not much of a "blackout" at all.