Conversation so far:
What types of things was Linus Pauling criticized for?
peace activism, his frequent travels, and his enthusiastic expansion into chemical-biomedical research all aroused opposition at Caltech.
Who opposed his works?
scientists who appreciated the contributions that he had made in chemistry, disagreed with his political positions and saw him as a naive spokesman for Soviet communism.

Question: What political positions made him unpopular?
Self-contained rewrite: What political positions made Linus Pauling unpopular?