It's easy to get to the obvious point that a large worldwide majority favors censoring the internet.
There has been a study showing that a large majority of Chinese are actually in favor of their internet control, over 90%. That's 1 billion people right there.
Studies in muslim countries consistently show that there, too, large majorities want internet to be non-free (and in many countries it is). Again that's close to 1 billion people.
And, again India supports it too. Assuming most Indian people agree with India's constitution that gives you a majority of "world citizens" without needing a single American or European vote.
The sad fact is that it is obvious : a world government would be an a lot more repressive than the American government, a fact that can not seriously come as a surprise to anyone who watches UN decisions (e.g. the UN human rights council, consisting of China, Saudi arabia, Libya, ...), who derise Israel's rough treatment of 2 women at a border crossing, WHILE they are themselves comitting genocide on their own people.
And, frankly, even most Europeans are in favor of outlawing "hate speech" (which basically means outlawing what are considered undesirable political movements. The problem is of course that 20%-30% (at least) of European citizens are members of these parties).
I've lived in Europe for a long time, and the effects of this go from mildly-scary (such as the de-facto outlawing of research that might alter our ideas about global warming, including the study ways to fix it through "artificial" means, like artificially increasing or decreasing cloud cover (Euro governments really don't like the fact that global warming could be fixed with 5 planes, or a decent fleet of automated ships, spreading reflective particles in the athmosphere). There's also downright scary ways liberties are curtailed in Europe, such as EUCD enforcement, which is way worse than the DMCA ever will be (but even the EUCD is child's play compared to muslim, African, chinese, or Indian internet laws).
America is the only country I've ever been where you can generally assume that someone you start talking to in the street is in favor of a completely free press, a completely free internet. The only one.
But America is less than 5% of the world population.
This is why you want internet control to remain in the US government's hands, against the "will of the people". All these countries, with the agreement of their citizens, would make the internet a tiny echo chamber that simply shows them how they were right all along.
There's the hope that since Texas wants the internet to prove the earth is only 5000 year old, and Saudi Arabia want people beheaded that suggest evolution happened, or that show their own genocidal history (or is it the other way around ?), this will somehow "balance out". Frankly, I doubt it.
The result will be quite the reverse, only non-offensive subjects will be allowed on the internet. Nothing even mildly suggestive. No history study at all, because most everyone objects to their own history (e.g. the American treatment of black slaves pales in comparison to the muslim treatment of black slaves. Then again, the holocaust pales in comparison to muslim treatment of black slaves). Things like GDP, that could be taken to "prove" that most countries (all except America and China) are worse than others, will be outlawed ... and so on and so forth.
In general "truth" would be outlawed. Because facts hurt too many people's feelings.