"Haha! I knew it!" Apparently the confirmation that animals are capable of love proves something for Reigen.

When Curufin mentions they should get going, Reigen considers something before gently picking up Nugget-chan. "Well, she might not be able to keep up...besides, we need to reunite her with the rest of the chickens! She's well-behaved, it'll be fine!"

He and Nugget-chan have a bond now. No chicken left behind.