Actually not to prolong it... but on a point of clarification
were the activities between pledges and actives or pledges and pledges, or actives and actives??
There is no doubt the actions were reprehensible but the collective - Theta Nu Epsilon itself, is (most certainly!) not NPC and not subject to NPC rules. Its member orgs may well themselves be NPC but the threats etc weren't perpetuated against members of an org to others in their org or wishing to become a part of their org.
So on a purely technical point I don't see that it fits the hazing definition - though it is unacceptable and no doubt the general attitude and actions of individuals are a far cry from the core founder values of the member sororities involved in Theta Nu Epsilon.
ETA:
Ohhhh MysticCat81! A pox on you for typing & posting faster than me! 