One problem is that the semi canon dark urge is a dragonborn.
If we ignore the (infertile) transformed humans for a moment dragonborn only appeared during the spellplague at which point Bhaal was already dead. So whatever connection the Urge has to Bhaal had to be created after Bhaals rebirth which was 10 years before the game.
Its more likely that the dark urge is Bhaal with amnesia.
Except the Dark Urge was active 15 years before the game.
I'd guess a powerful follower that Bhaal is now using to collect energy and followers. Durge may even be part of the plot to bring him back in the first place.
