Thats just not true. In fact, you have it completely backwards. Trump completely avoided talking about the protests during his trade war with china. He specificially ignored it in hopes it would lead china to come in on a deal. Supporting HK publicly would have ruined any deal he was working on.
In fact, i'm really not sure how congress supporting HK can even be used "as a bargaining chip against China".

Yea, that famous time HK protestors asked for city cops in the US to join them /s