If you accuse Russia, Belarus, Kazakhstan and/or China of widespread internet censorship, you act against one of UN's best interests: Preventing hostilities. If you know that almost all sovereign states in the world are members, you may realize how very difficult it gets to release such a paper with clear and directed accusations of naughty things, knowing full well that some of those naughty countries possess the means to cripple the world, either by means of economy or warfare. So you keep a low profile when addressing countries directly. It's simply in no one's interest to do that, it's better to "suffer" the fact a naughty country does not particularly adhere to UN chartas than to chastise a member for it and risking god knows what.
You also cannot expect the UN to have a clear opinion on internet censorship. Access to the internet is not a human right, let alone free-as-in-freedom access to it.
Your measurement of how many times a country is mentioned is the same bogus as when some manager rates the quality of your code by how many lines you wrote. What it especially doesn't say is that UN endorses or even supports censorship, that's an entirely subjective, malicious interpretation.