Your meat man is absolutely right. If all the deer that had old wounds, isolated infections, areas of gangrene. and cysts were discarded then I would bet that 20% of the animals harvested would go to waste.
I liken the situation to having a chunk of cheese in the refrigerator that get's mold on the end or the side. I don't know about you, but I cut off the mold and eat the rest of the cheese. The same holds true with an old wound on a deer and you're butcher handled in right.
Dave