I would think that one of the major reasons the NAACP is against charter schools is that employment in school systems has been one of the major gains that has been made by minorities since the passage of civil rights legislation.  It could be that rather than viewing it as a racial thing it has more to do with teachers in charter schools on average are being paid significantly less than those in public schools and this will serve to diminish a ladder into the middle class for minorities. 
https://www.chalkbeat.org/posts/co/2016/07/15/colorados-charter-schools-are-more-diverse-performing-better-and-paying-teachers-less-report-shows/