To balance things a bit, his request might make some sense from a monogamous point of view, and is a depressingly common starting place even for people who think they're trying to be poly (I don't consider it to actually be polyamory if you can't have a one on one relationship with anyone but your primary partner, but not everyone sets out with that mindset). From a poly POV his request is way messed up, but he's JUST beginning to consider these ideas, he presumably hasn't thought through all the ramifications of what he's asking.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.