Albrecht couldn't imagine that Hyrula would just grant him a free pass just like that. Besides, he wasn't even sure whether he could free her from her imprisonment or not. That's why her advertent words of letting him go sank in his mind like a stone thrown into a deep well.
Just then, Albrecht's mind shifted to the System and the unlocked 'hidden quest' it assigned him. He was supposed to defeat Hyrula and spare her life, not the other way around!
Seeing that he failed to complete the quest, he figured that the System probably wouldn't reward him for it. Then again, it was a better option than getting killed. In hindsight, Albrecht realized that it was an absolute insult to Hyrula due to their difference in levels.
Fortunately, Hyrula was lenient enough to spare his life, and one incomplete 'hidden quest' in exchange for her mercy was worth it.