He uses the words China and PRC interchangeably. The majority of the land in China is under the control of the PRC. Hence, the PRC represents the masses in China in the UN Assembly. At the same time, the people in Taiwan duly elect their government to work for the 24 million population. It is a legitimate government. Taiwan is not part of the PRC.
But in 1949, The Political delegation meeting of China declared to change the China's official nation name from Republic of China to The People's Republic of China. Even Taiwan delegates joined that meeting