> How is this different from saying “only people who have never sinned can speak out against evil.” With the added dollop of whataboutism?

You can't make a moral argument ("China is evil!") without being on moral highground. Having your own moral highground questioned when you're trying to paint youself as better is not "whataboutism".

There's two way how you can go about this argument:

1.) You can debate purely realpolitik - where morals don't matter and only the benefit of US or China hegemony is taken into account. This can be a hard sell though, mostly due to how current administration relentlessly attacks even their historic allies.

2.) You can debate on basis of keeping a free and modern society and how US keeps Chinese totalitarianism at bay. But then you will have to accept having your own morals questioned. Screaming about Chinese totalitarianism when the current US president actively avoids and attacks the US justice system trying to keep him accountable is hypocritical.

And we are free to criticize the current US President, and we are aware of his wrongdoings, as are all citizens of the country- resulting in a change in the way the political calculus of the country runs.

How is this in any way comparable to China where people have to come up with homophones/alternate words to literally get around armies of state censors?