That's a new one on me. I've found a lot of sheds over the years, and never anything like that. From being fused together at the base, and the brow tines being messed up, the rest of the antler stucture seems normal.
I also would say at least 5 1/2, maybe more.
If he was able to pass on this antler trait, I would think, with his age, by now you should have seen something with his antler characteristics. Probably the only way by sight, would be the narrow rack.
Have found sheds from deer with (I think to be brain disese) that a big chunk of skull structure well below the antler "burr", broke off when they shed it. And talk about stink from some kind of abscess, you could not imagine. Don't think he has anything like that.