If it was for Dorothy, why would they specify that the actress had to be black?
Because Dorothy is Tamara’s Grandma. It’s my crack theory and I’m sticking with it! 😛
I read something somewhere (probably tumblr) recently that said that unless a casting call actually specifies that a character is non-white, it’s an automatic assumption that the character will be white, and so anyone of a different race typically won’t even be sent to audition. Sad state of affairs if that’s really the case, but it would suggest that there’s a specific reason they want to cast this role as African-American if they made sure the casting call said it.