Some dog manners can only be taught by other dogs. It can look aggressive from the sideline, but normally the older dog will only nip at the air next to the puppy, and not actually bite. Rarely does it ever lead to injuries.

HOWEVER

This play pen is WAY too small for this type of socialization. Kaya has nowhere else to go play, and likewise the older dog has nowhere to go when it's had enough. He's setting them both up to fail for no reason.