Isn't "If they're not willing to play fair, then _we_ must play fair" the core of of US philosophy? It certainly seems to be the standard imposed on US civil rights leaders and the central message of the big speeches in superhero movies.
The United States likes to say (or at least pretend) that it is a moral society, that it is through staying true to moral standards of truth and justice that the US will ultimately prevail, and that if the US fails to uphold those moral standards than the enemy has already won. US pop culture heroes (from X-Men to courtroom dramas and everything in between) constantly espouses this perspective.
From that perspective, the most important thing the US can do is keep an open communication channel with people in China so that they can ultimately see the error of their ways and come around to a US way of thinking, and cutting off communication with people in China is making the US more like China. It may be a self-righteous, egotistical, or even completely delusional way of looking at things, but the officially stated goals of US foreign policy frequently are.
I think the real underlying principle behind the United States is that the US says one thing and does another. Believing that the US has principles, etc. instead of just realpolitik in 2020 is naive. You have access to the all the information in the world.