What compells a 100 year old man to fly 14 hours to China (with a medical team)?

Maintaining “relevancy and influence”? Doubt it. What about just a “private citizen” on a holiday? I doubt that even more.

"The BBC went so far as to suggest that, “given his outsized stature in China, [Kissinger] could act as a backchannel for U.S.-China negotiations.”

The State Department threw cold water on that last possibility in their daily briefing, stressing that Kissinger was traveling as a private citizen and not under the aegis of the U.S. government.”