This quote points out that before diversity factors come into play, all other things need to be equal. That suggests to me that should all of the remaining writing samples and qualifications be at the same level, only then do diversity elements emerge as a kind of tie-breaker, if necessary, which makes sense given that for a very long time, MFA programs were composed of straight, white men.
What I had a problem with is in your earlier post, when you stated that "If someone drops from consideration, they pick someone on the waitlist who will preserve the diversity they were looking for in the incoming class." This made it sound as if diversity is the primary element that determines if someone gets taken off a waitlist, as opposed to, say, their actual abilities as a writer.
I point this out because MFA programs can be difficult spaces for many POC writers who are often seen as having a place only due to their role in diversifying the program, rather than their skills and academic potential.