The tweet "Fight for Freedom. Stand with Hong Kong" is the exact slogan violent protestors in HK uses every day. It's not "freedom of speech" but an implication of HK independence. You cannot take the words literally. I will give you another analogy -- no people in China understands why "All lives matter" offends the black community in the US, because why on earth would anyone object to all lives matter, right? Do Chinese NBA fans have legit rights to be offended by his tweet, I personally think so. Does this legitimize Chinese government's NBA ban, absolutely not.