Polyamory is very cool for people who are wired for it. A whole lot of people aren't, and that's okay. And some people could be wired for it, but they have a whole lot of self-work to do before they'll practice it well.
It works for me because I know that I never again want to presume any semblance of control or authority over any partner's absolute right to seek out joy and fulfillment by forming however many ethical and consensual relationships they wish, of whatever style they wish, with whomever they wish, for as long as they wish, and I insist upon the same right for myself.
Jealousy is just not an emotion I experience. Envy, yes...envy being wanting what someone else has. When I see a partner of mine having a particular dynamic with another partner that I want to have with them, I feel envy. But not jealousy, which is not wanting someone else to have something of yours. That is, I don't feel anxiety about their other partner "stealing them away from me." Anything lacking between me and a partner has nothing to do with anyone else not in our relationship; if I feel something is missing between us or want things to be a certain way, it is incumbent upon me to speak up, and vice versa. Outside of our relationship, I cheer my partners on in their other connections because love is fucking amazing, man!
He'd probably do it because of his hatred for "aLphABeT PeOpLE!" like his own kid. That fucking prick. If he were on fire, I'd piss on him, but not at the base of the flames.