I think it would depend on where you lay on the political spectrum. The first indochina war began in 1946 and ended in 1954 so this overlapped with McCarthyism and anti communist sentiment in the US. So many, especially on the right wing, would have seen the support for the French as a force for the greater good and the fight against communism. There is plenty of hypocrisy in this argument due to the fact that once upon a time, the US was a colony itself fighting against its colonist. This was recognised by many moderates and people on the left. There were also, of course, those on the further left who believed in non interventionism and even perhaps the government they were fighting against wasn’t so bad. Although I think it’s safe to say that US public opinion wasn’t strongly formed on this issue until later on in the war.