I believe its to not seem weak on "the china issue" to the local audience. Like "We're going to try diplomatic means with the chinese (again), because we're the good guys who don't want a war, but don't you worry we see them for what they really are."

Then any concessions the US makes to the evil chinese "regime" are reasonable realpolitik necessities because of very complex diplomatic issues with a country thats notoriously tough to reason with and at the same time any concessions the chinese make are not good enough because it didn't bring that evil "regime" to its knees.