Khan would have been ready to jump at the offer after his father died. After all, he had promised to save his loved ones and the universe as a whole on Bret's deathbed.
Khan would have also been ready to agree to those terms after breaking up with Monica. His curse had become his life's mission at that point, making him more than willing to sacrifice everything he had and was to ensure the universe's safety.
Yet, that time was now long gone. Khan hadn't only found another reason to live. His mindset as a whole had also changed, affecting his element and the kind of existence he was.
There was far more to Khan's life than his curse now, and the cold hand holding his own acted as an undeniable reminder of that.