Noah had his reasons to come out of the cave. He had never liked to remain in a safe place for too long since it was easier to improve when facing adversities. Also, his last project required him to explore the Immortal Lands.
The red crystals obtained in the Evolution Pit could improve his companions since they carried features similar to his black hole. They weren't an organ that could benefit every function of his existence, but they could perform the same purification.
Noah didn't dare to test them on his companions right away. Night, Snore, and the Demonic Sword were a core aspect of his superior battle prowess. He was already stronger than an average hybrid, but the three creatures brought his might far beyond what a single existence at his level could wield.
They were one of the main reasons why he could seize benefits where others ran away. Risking their structure with materials that he didn't fully understand was idiotic.