I am well aware of the US at the time and yes there were plenty of Americans fighting the good fight including more anti-nazi sentiment than I had previously thought. You still aren’t addressing the topic which we are here to debate.
Because they were not fighting Axis because of racism. It was war against foreign power. What Nazis gad against other groups was not common knowledge. It was only discovered in 1944-45, when they started freeing konzlagers. And even then Allies had troubles believing what they were seeing, despite all the evidence.
Hence racism was never an issue for them. Especially for the US.