I don't like to state the obvious, but here goes:
The reason girls showed up to a meeting of a Jewish-interest sorority who have no interest in or clue about Judaism is because MTV is filming the sorority. Got it? Good. Don't make me repeat myself.
Please also keep in mind that Sigma AEPi is NOT a member of NPC...therefore they do not have to follow the rush rules, terminology or anything else set down by the NPC and its member groups. The same would apply if a chapter of a service/social, professional/social or NPHC group was being filmed.
Presently they are associate members of UC Davis's Panhellenic, but if they become full members I would assume they will have to follow the same rules as the other groups in the campus Panhellenic with regard to rush and such.