What you have there is Podermatisisis, which is often used interchangeably with the term Bumblefoot, but is different in the way that there is no laceration or external core, and usually just consists of swelling. The area can develop when the bird is housed on hard/rough bedding, or housed in areas where sharp objects can pierce the epidermal layer of skin.
It should be taken care of, as the area is almost always infected, and if left alone will spread further up the leg. If I were to see that, I would probably start soaking the foot in Epsom salts in hopes to reduce some of the swelling, and then try to make a small incision of the area with a sharp sterile scalpel, and excavate some of the puss out. After that, pack the area with Neosporin, or silver silvadene cream, wrap gauze around bandage with vet wrap.
