The Chinese government’s decision to crack down on Hong Kong presents Trump with a difficult decision. On the one hand, he truly values his relationship with Xi, he doesn’t want to engage in any kind of a shooting war, he has no interest in promoting liberal democracy and human rights in Hong Kong (or anywhere else), and he knows an escalation of the trade war will cause his beloved Dow to plummet. On the other hand, being tough on the Chinese is the centerpiece of his campaign. What will he do?
Trump typically deals with contradictions in his policy by dividing the labor and sending mixed messages. You can expect that to continue with Hong Kong. He will authorize Pompeo, other members of his administration, and prominent GOP members of Congress to make very hard line statements about human rights in Hong Kong, while he himself says little or nothing on the subject. By doing that, he will think he can have the best of both worlds.
What it will mean in the real world is that the Chinese will take any objections from us with a grain of salt, and do whatever they want.