Spice was not banned at the time of the alleged occurences (it is now). In fact the article you should read is the actual ESPN the Mag story on it. Pretty sad stuff about how dangerous Spice really is.
http://espn.go.com/espn/e60/story/_/...-espn-magazine
So to me the legality of Spice isn't entirely important, its more the lack of control that appears to be a pattern at Auburn. If USC, Ohio State and Miami all got hammered because of the "Lack of institutional control", I gotta imagine Auburn will too.