I think it's just a joke. I'm pretty sure the book of mormon didn't look like that when Joseph was still around. Maybe it's signed by a Joseph Smith not the Joseph Smith.
I emailed him and asked if he was Mark Hofmann. He replied "ha, no" then asked if I was interested in his signed BoM. I replied that I was pretty sure Joseph Smith hadn't signed his book and asked him what the real deal was. This is his reply:
what do you mean real deal? They are signed by joseph smith thats pretty cool! i also have the silver plates that ill sell with it. most people havent heard of that but its the rough draft to the gold plates!
I think he is Joseph Smith reincarnate. I'm going to ask him if his name is Joseph Smith.