Isn't this line of thinking sort of excusing the thing that the very program is supposed to address though?

More concretely, the need for this program is described as a welcoming environment for black girls to get into STEM, because black girls are discouraged being that they are "outsiders".

Why would a white girl not feel like an "outsider" as a program specifically for black girls?

As a minority in the country I was born in, I know what it means to feel like an outsider my whole life. It's fine for a kid to learn what it feels like to be an outsider for once in her life, it builds empathy.