It sucks that it happened, but I think he was with the best family for it to happen too! Great that you already had a place for him to get some sun! The wound looks good, and I agree, it looks like deep tissue bruising. Here is another hen who lost part of her arm and also had the green bruising...
You did great! Personally, i would try and get him off of ceder bedding. The aromatic oils from it are not very good for chickens. Short term use is definitely not a big deal though. Otherwise, I think you have done completely amazing work!
I personally haven't had a bird THAT injured, but I...