Interestingly enough, these responsible poly folks are NOT involved in HAI! In fact, one man in the local poly group (who has been involved with HAI also) said that he agreed with me that HAI is fostering an "irresponsible" form of polyamory.
I don't remember HAI fostering any form of polyamory.
I remember peter talking about his experience, which is how he and his choose to set things up. (Open relationship)
One thing I've observed in watching different poly email lists, is that there are a lot of versions of what poly is. For some, it seems to be something that's much closer to swinging. (Hi, I'm poly, want to fuck?) For others, it's about long term, or lifetime commitments, and not ever something to enter into lightly. As long as everyone in the group is in agreement about what's going on, I don't see the problem. Now one of the major pitfalls of poly is that frequently people aren't open and honest, and so things go off the rails for that reason.
At no point though, did I get the impression that HAI was promoting poly, monogamy, or any other form of relationship. I do see that they are neutral to the form of your relationship, giving you tools to open your eyes and get past fears that are holding you back.
So it's hardly a surprise that when people go to something like hai, they may change, and sometimes in very profound ways. This may not be well received by their partners, depending on which way they changed, and which way their partners changed. I know I changed a lot. Fortunately lori and I changed in very similar ways, and it's been wonderful for us.
I never got the idea from hai that poly was "the right choice", but just that it was an option that works for some people. I was exposed to the idea of poly long ago, through heinlein (like so many people) and although at the time I thought it was a beautiful thing, I never thought that I would see it in real life.
HAI honors monogamy. You are welcome to do the workshop with the person(s) you came with, or mix around as you choose. Lori and I had a bit of a conflict at first, in that she wanted to stay with me (fear) and I wanted her to mix around, reasoning that she's got me 24/7, and she might get something valuable working with others.
We compromised, and she did some with me, and some with others, and that's working out just fine.
Getting back to the original question though, is this a cult?
One of the hallmarks of a cult, is insularity. They want you to only look to them for answers, and they sometimes punish their members for allowing outside thoughts/information in. (scientology)
That's not the case with hai. At no time were we told or pressured in any way to cut off communication with others, or to only look to hai.
The only pressure I felt there, came from ME, wanting to push my boundaries hard and break out of the old patterns which were clearly NOT working for either of us. I did that, and the results were much better than I could have hoped for. It's been almost a year now, and we are about to go back for level three.. We are closer now than we have been in many years, and really beginning to have fun again, and be more like a young couple in love.
We just choose to share that with others. Our choice, YMMV, IANAL, ETC.