That's because there's no threat to them. If the situation was tenser, and there was some open controversy about Hawaii, with another superpower taking sides, they could do all that, and worse.
It's not the "liked tweet" itself, it's having come into attention, people demanding something to be done, media blowing it, etc.
Tons of similar gaffes go by without an incident as well...
There’s really no good reason for the decades long embargo against Cuba except that the US considered it an enemy all nations partake in to pursue political goals.
(Why bring up US foreign policy again? Many don't agree with those decisions either and it's unrelated.)
If you meant just the American people, well not all Chinese side with China on the Tibet issue, but most do. But then that’s personal opinions and you can’t really blame them for having a personal opinion.
Using political leverage to force an outcome is inevitable, and frankly, discussing right or wrong on the matter is pointless as you cannot ever achieve politically neutral policy. All policy is enacted with a certain goal so it cannot be neutral by definition (unless your policy does nothing).
Either China wants Tibet as part of its territory or it doesn’t. In either case it will use its political powers to further whatever the goal is.
Of course not. They'd just ignore you. Not force you to suspend online sales to your 300 stores in the country. Why is there always someone willing to twist things into a pretzel in search of moral equivalence when it comes to China or Russia? There's no pot. There's no kettle. Using your leverage to force a company to stop doing business for a liked tweet is uncool for any country.