@DizzyDazzle
from his point of view, that's exactly right. That's fucking huge godlike talking bird that lives alone, why should he care? Law of the jungle - you live how you want, and do what you want, and if you are not strong enough for that - you die. Simple.
Griffon specifically ask him if he think that he can lose, answer was "no".
So, he want a female, and he believe that he will win the battle for her. So the desicion should be obvious.
Although your "LOL I'm a bird" perfectly hit the bullseye. He is a bird, not human... he can only give advice from his own PoW. But well... despite the fact how awful it sounds in that chapter, the problem isn't just in "i want her". The problem is that Rigar is an asshole. I don't know why Almus even think that if he let him become a king, he could maintain amicable relationship with him. Civil war is already inevitable, and the more time he wasting, the more powerful Dibel would be in their inevitable confrontation.
Well, ofcourse, unless he would completely surrender to Dibel and become his bitch. But it's obvious that Almus isn't planning that.