I would be surprised if this animal didn't get an infection, all that necrotic tissue is the perfect environment for bacteria and other pathogens to grow, as all this 'nutritious tissue' supports the pathogens and has no vascular supply (thus no penetration by the immune system). In my opinion it should be surgically removed and cleaned up, and it should be given a series of antibiotics, before it gets worse. You may easily end up with a case of septicaemia......
Regardless, all the best with this guy, hope it pulls through
Regardless, all the best with this guy, hope it pulls through