I agree with you that a lot of focus is being thrown at your terminology and very little on welcoming you or helping answer your questions about polyamory, how it might work for you, what challenges you might face and how we have overcome those challenges in the past. Many of us have fought through these kinds of situations, and I think some of the pain of those memories is coloring the replies you've been getting.
I have been in a sexually unequal relationship for many years. I desire sex 4-8 times a week, while my partner only wants sex 12 times a year. Do you read Dan Savage? He talks a lot about the situation. In relationships with a wide sexual desire disparity it is usually the case that the less- or asexual partner's needs trumps the more- or hyper-sexual partner's needs. Many of us have lived with this situation, loving our partner and feeling undesirable, and don't want to be pathologized any more than you do. On behalf of those who got a bit prickly before; sorry. We're all in the same boat, just at different ends of the spectrum. None of us needs to be labeled as "too" sexual, any more than you should be labled "not sexual enough".
Anyway, enough about us. I'm glad that you and your husband are exploring polyamory. My partner and I have been poly for about a year, and while we've experienced some turbulence, it's been really great! I do have some advice for you:
1) You have arrived at polyamory as a way to help your husband feel attractive and sexually fulfilled so that he can love and cherish you the way you both want. It will be much easier for that arrangement to work if you have as few restrictions on his partners as possible. Of course it would be wonderful if his secondary became a third in a triad (so many snuggles!), but if you're both looking for that element there may be people well suited to being his secondary partner who he passes by or who get scared off because a triad isn't what they want.
2) Remember to think of your husband's partner's perspective. It's really intimidating to be with someone who is so committed to a long-term partner. You can do a lot to make that person feel welcome and safe in her budding relationship: cultivate a relaxed, warm attitude, be available to talk but have not demands or needs of your own. If that person is well suited to your husband, the relationship he has with you, and the lifestyle you are embarking on it's likely that your overtures will be well received and a genuine friendship will grow. Maybe that friendship will grow into love, intimacy and a shared life. Maybe not.
And finally a question: are you also looking to find secondary partners, perhaps who are similarly grey-asexual?