The later half of the 1910s and the 1920s saw the early horrors of the soviet union, you also had quite a few attempts by socialist and far left groups to over throw various governments and quite a few acts of left wing terrorism such as assaults, murders, distruction of private property that kind of thing.
It is in that context that you have a lot of people who were quite reasonably leery of left wing politics notably communist and socialist polititions.
I am also surprised that you want to bring up that comparison when talking about minorities because it was a democrat president Woodrow Wilson who resegergated the military.
I want to repeat that, before Wilson the military was already desegregated, the democrats were the ones who publically undid 40 years of progress on that front, and he kept this policy up during a time of war when the nation needed all hands on deck. It took until 1948 until Truman desegregated the military...which you know good for the dems cleaning up the mess they created in the first place..
I mean if Woodrow had simply minded his own business and not fucked with the armed services we could have done the whole civil rights thing a generation earlier but you know you take what progress you can.