Huh. That's a pretty interesting question. I mean I guess it's still better to have a white actor playing King then a white actor playing King in blackface.
The comparison to Shakespeare is interesting though. I think the difference might be that in Shakespeare, an actor or actress isn't really playing a historical figure- they are playing "Shakespeare's version of a historical figure". So like for example, someone playing Shakespeare's Prince Hal/Henry V on stage could be any race (or for that matter, any gender), but a historically-accurate biography about the man would probably want to cast a white guy.
The King play sounds more on the historically-accurate biography side of things.
Funnily enough, in the last week or so, another case came up involving a play with Indian characters done by one of the local high schools and the playwright yanking the license when he found out that non-Indian characters were playing the roles.
Ah, here it is, Clarion University and "Jesus in India"
. Three Indian characters were played by two white, and one mixed-race, actors. Apparently The Mountaintop was not yanked as race was not stipulated in the licensing, while Jesus in India apparently never had a contract to perform it (which is horrible on the part of the producer). Nevertheless, the article states that the playwright, and the licensing company, has the right to pull the production even if there are no stipulations in place, which would not surprise me, as most of them have a notice somewhere saying that the licensing company can withdraw the license at any time for any reason.
The playwright reacts
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Interesting. I like that the author acknowledges that this comes off as a bit hypocritical given he was just praising the work of black performers playing white presidents in Hamilton but it makes sense. Hamilton isn't intended to be taken seriously. Although honestly... I'm having trouble being outraged over the idea of the white actor playing King since I do a lot of Shakespeare where there really are few boundaries for who gets cast in what, but I understand that race is tricky.
I was a bit more surprised that, in this day and age, a writer can put race stipulations in the license for a stage show.