He was a radio operator and he claims that they weren’t allowed to demolish railroads from China or ground-to-air missiles and other things from the Chinese because the U.S. didn’t want to affect trade relations. Growing up I took this claim as fact but now I’m not sure.
For clarification, do you know when he was a radio operator in Vietnam? I ask due to frosty relations between the two powers between 1949 -1971(2), and a notable US Trade embargo with China, starting from 1950 until the famed dethaw, discussed in 'China and the US Trade Embargo, 1950-1972', Xin-zhu J. Chen https://www.jstor.org/stable/44288827?seq=1 (Make an account, and you can read the whole journal free.)