I managed to find footage showing the Chinese delegation, one person is seen remaining seated during the walkout. Presuming the six seats are divided evenly between China and Chile, two seats reserved for China are empty, but I don’t know if that was meant as: “we’ll have one low-level guy listen and have the others leave ahead of the walkout for strategic ambiguity” or if that’s standard practice for them. They’re just out of frame in routine shots of the whole assembly during other speeches, so I can’t compare.

What I can say is that he isn’t China’s Permanent Representative, who is portlier and has gray hair.