What does the back of his legs look like?
This is the front of the legs we are looking at.
Possibly impacted feather follicles, but it's unusual that it would be on both legs at practically the same place.
Could the vet not offer any suggestions?
Even in a fight or attack - it would be odd for the wounds to line up like that.
Cancer comes to mind as well, with all that bubbling raised follicles.
Keep the wounds cleaned with Chlorhexidine, apply very thin triple antibiotic ointment. For this, I think I might would cover/wrap the wounds overnight while he is roosting, just to keep his feathers off the wounds and him cleaner too. Take the wrappings off during the day so the wounds can breath.
There's no lice or mites on him is there?
He's a nice rooster, I hope he recovers.