You are right. Whatever treaties were signed, a Democrat Department of Justice would get a cackle of Democrat judges to rule that the treaties are “null and void”. There will be four star generals and admirals sitting in their Pentagon offices supporting the Democrats. Communists will burn the Taiwan flag on American streets. Biden and his controllers will assure the American people that there is “peace in our time”.
At this point if China attacked I'm not sure I'd count on the four stars to follow an order from Trump to defend Taiwan. I personally think that Trump was stopped from deploying the national guard because SecDef let him know that there would be open dissension by the pentagon leadership (including SecDef himself who already let his opinion fly in public, frankly) and that would have been a worse disaster than looking weak for not following through on his promise to end the riots (which looks bad enough).
It took less than that during Nixon’s resignation between Ford to let the S. Vietnamese be invaded without coming to their aid. I was on DRF1 and headed into cattle cars when they called off our jump into Saigon to defend the Embassy.