This is in no way comparable with trying to weasel out of paying for a stay by taking advnatge of a clerical error.

ICHG are obviously completely aware of the way that their supposedly "targetted" promos can be used. That they have consistently choosen not to make changes to their software to limit registration to specific members is a clear indication that they made a conscious decision to keep things the way their are.

Thus, this case isn't even ethically comparable with a "mistake rate", let alone a "bank error in your favor" case like this. In contrast, we are taking advantage of features of the program which, while ICHG choose not to draw attention to them, are evidently a conscious choice.

So, to answer your question, I regard it as a "good thing", beacuse it is to my advantage, and reagard it as wholly ethical because we know that ICHG are aware of the situation (see the note at the beginning of the promo sticky) and choose not to change it.