There is absolutely no reason to think that race is in any way involved in Patti's comments or their motivations. Additionally, to suggest that they are is enormously condescending to black people, suggesting that they cannot accept or even hear criticism without being relegated back to places and times of harmful discrimination. Being infantilized has never lifted anyone up.
Oh, and also note: Ms. LuPone has a well known habit of speaking her mind, spewing her anger and chastising those for she holds a grudge. Please ask Glenn Close, Trevor Nunn and Peter Gallagher if it takes ethnic tension to earn Patti's ire.