If you read the article it is clear that it was not about "musical scoring of Shakespearean film." (The film has little if any music in it--even the credits are silent.) It was just about the play, for the purposes of comparing it to Verdi, so any reasonably full production would have served the purpose.
There are indeed shifting politics, but the shift happened a decade or two ago.
It is shocking in many ways that this film would be shown. First, you do not have to be especially culturally sensitive to know that blackface is likely to offend most students. Second, Olivier's performance may have been good on stage, but on film it is so over the top that it tends to inspire giggles.