We don't know what exactly Morghur is. But his existence and presence is described in a way that makes it look almost like a spiritual force being incarnated upon the world and setting out to wreak havoc.I liked your earlier theory enough I fiddled with it to explain something it didn't before, but this doesn't track to me. Morghur isn't actually a daemon, he's just got mondo warp powers and is technically immortal because he just reincarnates into some poor schmuck's body through the Warp if he gets killed. So, yk, there's thematic overlap but nevertheless he's still a distinct entity. And if it was that easy to change how something thought/viewed you when binding it a lot fewer daemon-summoners would get eaten by what they summon.
Furthermore, that "'just' reincarnates into some poor schmuck" and "has mondo chaos powers" is a very suspicious thing for a being to be doing or be described as. It's... I don't... hrm. Remember when BoneyM quoted people talking about Damsels and using multiple Winds of magic and said "In that case, put a lot of asterisks and question marks by the word 'human''? That, basically. Reincarnating like that? And having magical superpowers like that? That shit ain't normal.
Morghur's existence is partially spiritual in some way. Maybe he's like a Treeman, maybe he's like a Daemonhost, maybe he's like an Everchosen, maybe he's like a Daemon, maybe he's like a fucking ghost or solidified walking dhar or whatever the hell.
Regardless, I do think it's possible to bind him. If he's not a daemon, then he should be bindable the way Giants and Dragons are bindable with Kadon's skills.
If he is a Daemon, he should be bindable the way Dawi Zharr do daemon-binding. Or the way you get Daemonweapons.
Or he should be bindable as something in-between.
And then, throw in the Runes of Valaya to purify all the Dhar he wafts out, and you've got an explanation for why this place is not a writhing chunk of hell-space despite being host to Cor-Dum. And also why it's desertified, too. Things get transmuted by his aura, Dhar gets released, and then the Runemasters' art and workings burn away the Dhar.