I've eaten a few different critters that have had some battle wounds, my concern with this one is the overall condition of the rest of the animal. If he just had a poke in his side that was healing up I wouldn't hesitate for a second to eat him. This elk has been sick for quite some time to get as skinny as his is. I bet he wasn't much over 500 on the hoof. Both hind quarters weigh about 70lbs...not each, together.
I also don't know if he's okay to eat just because he tastes okay?
It's hard to know if that injury is what was causing all of his problems, or if he had other problems and that's why the injury wasn't healing?