I agree with your observation, however they act to establish a kind of background about the film's subject matter that would have to be explained to audiences not familiar with the time period. The best way to do that would be through the two characters representing the thousands of people that were quietly persecuted behind the headlines by the extreme right wing conservatives led by McCarthy.

Did you notice that around the time the film was released, several conservative commentators were saying (in so many words) "Oh, McCarthy wasn't so bad... he got the Communists out of the government, didn't he?"

That kind of "glossing over the bad" thinking has given us Bush and his extremists taking our liberal system of government apart, bit by bit, piece by piece, year after year, as long as they're in power, until all our rights and privileges have been eroded to non-existence.