Nothing against Delta's FAs, but people have been making the Harvard comparison for years, including pilot groups. Virgin America used to say the exact same thing about their pilots at job fairs, and the US Airways FAs said it about themselves back when I was a new hire.
I understand that they want to feel 'elite' by making that comparison, but this is sort of a pet peeve of mine. Very few people apply to Harvard unless they feel they're at least in the ballpark to being admitted, so Harvard is making their selections from a pool of applicants that are already near the top of their peer group academically. Delta FA applicants are coming from a cross section of society where the only criteria is to have a HS diploma. It's not the same thing.