Abrams has a fairly good record of diverse casting in his shows and films, from Carl Lumbly in Alias
to Lance Reddick in Fringe
to the mostly black cast of Undercovers
to Maggie Q in Mission: Impossible III
to Faran Tahir in Star Trek
to Michael Ealy in Almost Human
. And we know that except for Cumberbatch, every actor he considered for the role of Khan was Latino. Ideally they should've gone for a South Asian actor (I think Naveen Andrews could've worked), but at least they were trying to match Ricardo Montalban. So either they sincerely thought Cumberbatch was the best actor despite his ethnicity, or they were pressured by the studio to cast him instead of one of the others. This was a questionable decision, but I don't think it's fair to paint Abrams as prejudiced because of it, since the rest of his record doesn't bear that out. Bay, on the other hand...