Well, please, lets. Is it bad? No, it is not. It's meant to expose and encourage some kids who, statistically, are otherwise unlikely to be exposed to computer programming in the same way that other kids have been by providing a comfortable environment filled with others like them.
I suspect, however, since there's more comments than upvotes here, that a significant amount of Hacker News readers have a problem with that. I read comments like, 'oh, they should allow kids of all colors and sexes in there', and I think to myself, are you really so blind to the reality that the kids in this highly underrepresented demographic would be crowded out by other kids who already have the privilege of and exposure to computer programming.
No one is trying to prevent anyone from being programmers with Black Girls Code. They're just trying to create some comfortable space for these kids so that they can grow their computer skills as they grow up and become tech-literate adults in our ever-increasing information economy and culture that can compete on a fair playing field. That so many people here have a problem with that is highly concerning.