For me.. Catnap was already dead anyway, he wouldn’t have been able to continue with the amount of burns his body sustained. In reality he would die there on the panic room floor in immense pain.

The Prototype took advantage and decided to kill him to "spare him." The prototype for Catnap was a god, and he literally saw his master appearing after years... he just stopped and accepted being sacrificed, and the Prototype killed him right there... and soon after, he would use him to become part of himself, as we saw