Simon, I think it depends on how high a bar you set for a cult. I suggest you be a bit careful when talking about this issue as people have different opinions and some hold to their opinions very passionately. Words like "cult" are tricky, because they're basically bad things, yet the meaning of the word is a little hard to pin down. It's hard to put an exact definition on the word "religion," for instance. As far as I know, some experts agree with you, some do not.
You feel that physical control of members is necessary to consider a group to be a cult. Many of us don't think that's the necessarily the case, and this is one of those areas where people will debate over what a cult really is. I would agree that the Society probably isn't as bad as a cult that does assert physical control over its members.
Emotional control, for me, is an adequate substitute for physical control. So for me, the bar is a bit lower than it is for you.