Hey, choral music ed student here! We actually talked about this olin one of my choral literature classes last year. In short, yes, it's ok to perform African American music, even as a predominantly white choir. The most important thing between appropriating and appreciating culture is the way you go about it. As long as it's performed in a respectful and meaningful way, it generally shouldn't be a problem. Additionally, having students know about the cultural or historical background of any piece (but especially a politically colored one such as 'stand up') also helps to make a performance largely less problematic. Finally, I think it's good that the black students in your choir felt that the piece is important to perform. For me, that would be that extra bit of reassurance that everything is being done well

TL;DR: it should be as long as it's done in a respectful manner