He admits he is not 100% accurate.
You may have missed the point.
Not everyone understands and has revulsion to the terms Leftists, Progressives, Socialists, etc. There was even a survey a month or two ago that showed young people were open to Socialism.
However, over the decades people have come to understand that Liberals are not friends of our type of country. Therefore, Rush said, use a term that people understand to denigrate and label our opponents.