I believe that the decision has been made to abandon Taiwan. Even before the Afghanistan surrender. The administration has indicated that it will not stop aggression, anywhere, for any reason, unless it furthers the desires of the Socialist movement. In effect, this administration is orchestrating a ‘de fact’ surrender to the socialists, both foreign and domestic.
Also, any argument that talks about the lack of a written doc protecting Taiwan is way off the mark. BeijingBiden has already indicated that he respects no law, even US Const. See rent/eviction position.