Of course the links confirm it, but you don't need links to assume that the song wasn't some spontaneous happening by a few racially insensitive punks. What more ridiculous, imo, is the knee-jerk reaction by SAE higher-ups/ alums when they've probably known about the song forever and likely participated themselves.
I haven't been inside many fraternities, but the fact that a bunch of sheltered, mostly upper-middle class kids from the suburbs think it's cool and fun say or sing racist stuff isn't surprising at all.