Reagan, a devoted defender of Taiwan, was incensed, and tried to reach Nixon the night of the vote. Reagan despised the United Nations, which he described as a “kangaroo court” filled with “bums,” and he wanted the U.S. to withdraw from full participation immediately
https://historynewsnetwork.org/article/172680
What if in retaliation for the UN voting to recognize the People's Republic of China and expelling Taiwan, the United States announced that it was withdrawing from the UN completely?