IT wasn't blackface in the generic sense which would be racsist. She was imitating the character "crazy eyes" in "Orange is the new black" (black in terms of clothing not skin color, that's just a coincidence.)
If you've ever seen the show, you'd say, maybe OK.
Still it was poor taste, how many people would know?, and when another (thousands) choice exists, why not go another way?
And +1 to Demon's point.