While I fully agree that (while we sometimes do our best to pretend otherwise) US constitutional protections of speech are vastly better than the world's in general, even the parts not commonly considered to be despotic hellholes; and I think that letting Team Morality into the TLD business will be a clusterfuck; it isn't clear that ICANN being under US contract ensures that US standards prevail on the internet; or that the aforementioned clusterfuck is avoided.
Since ICANN has no actual teeth, aside from the inconveniences of being incompatible, it is already routine for entities of various sizes; from home networks with cheapie routers whose embedded DNS servers give themselves a name friendlier than 192.168.0.1; to companies trying to keep employees off facebook at work; to the Great Firewall of China and the 'Halal Internet' of Iran; to implement a 'mostly what ICANN says; except when we disagree' assignment of internet names and numbers; and when you have legal authority(and sometimes direct ownership or control) of the ISPs, that counts for a lot.
On the Team Morality and the TLDs side; the Department of Commerce couldn't, or didn't feel like, keeping ICANN from treading the road of total insanity of allowing gTLDs to proliferate like mad. That terrible plan already has the trademark lawyers, the morality police, every last idiot with sensitive feelings about anything, and so on up in arms and likely to keep squabbling until the heat death of the universe.
If it were actually the case that ICANN is a good vehicle for advancing America's better nature worldwide; and that maintaining American operation of ICANN was instrumental to keeping it that way; I'd be 100% against letting anyone else touch it. I'm just not convinced that either of those are particularly true. It is easy, and people already do wherever they have the requisite power, to operate "ICANN, minus what I dislike" and have it stick against all but moderately determined users. Some countries do it much harder than others; with the US most enthusiastic when copyright is involved; but ICANN has zero effect on how easy it is.