Jacob became silent after hearing Immortika's derided question because, just as Immortika articulated, even if he knew the true origin of the Gluttony Mask, he wasn't going to give it up. In fact, he would be over the moon after discovering that he had acquired a Universal Godly Artifact!
However, now that he knew the entire story and relationship behind a Universal Godly Scripture and the Universal Godly Artifact, he knew that as long as he had it, he'd eventually run into that woman.
If he had known this, he would've been more hesitant to use the Gluttony Mask, but alas, he had already become its master, and now that he knew what kind of treasure it was, he was even more unwilling to give it up or stop using it.
