As per statements by the white house[2] and other branches[3] that twitter account is an official channel of US Government policy, I think this is reasonable and generally accepted[4].
If you don't like Donald Trump's conduct in office (I don't, incidentally) you and millions of others can organize and likely prevent him from getting reelected. If you don't like Xi Jinping's conduct in office...
...you can organize and likely prevent him from getting reelected if you don't have to deal with gerrymandering, can get votes enough to overcome the vote weighting of the electoral college, and if there's no foreign sabotage of the election.
I agree China and the US are in radically different places, but there are serious problems of some degree in many places right now.
If I was a Chinese citizen I probably 1. wouldn't be around anymore or 2. not be nearly the same person - I'm quite thankful I grew up in a society that let me read Marx for Beginners[1] at a young age and has allowed me to express myself - I support the HK protestors without any reservations and, even with the oval office being as it is, I think the US's government is far more fair and held to account than China's - still, it is counterproductive to the freedoms of America to constantly exaggerate those freedoms and hold patriotism over honesty. America may be a shining city on a hill but up close it's pretty clear to see the parts that are tarnished - we can work to fix those issues if we accept that they are issues, or we can insist there are no issues and let those hard fought for freedoms get taken away.