River--- It was a very interesting post, thanks for sharing.
If I had to guess, it sounds like he's typical of a lot of gay men in "open relationships"---sex with others is ok but you're only allowed to love one man. And in that same breath, they'll turn around and say something negative and/or stereotypical about polyamory ("dangerous" in his words). I know...the irony!
And the sad fact is, I'm convinced most of the time, these guys in open relationships would actually benefit
from true polyamory. (It's certainly more healthy than sleeping around and trying to act like you can never love anyone you screw.)
Sigh...it can be exhausting trying to find gay men who actually know what polyamory is about.
To the question at the end of your post...should you forget him? Well, if you can be a friend-with-benefit with him, knowing that's all he wants, then more power to you. Nothing wrong with that...have fun, play safe, etc.
But...only you can know if that's what will make you happy in the longterm.