Well, he says its to make sure that the playing field is level for all players- no one can get an advantage by having a particular book that the other players don't have. This is quite legitimate.
However, after 20 years, I know him better than that. He simply doesn't like new stuff much.
When it comes to gaming, he's extremely conservative. He refuses to learn any RPG besides D&D. This will be his first 3.5 campaign- up until late last year, he refused to even buy a single 3.5 book. He was the last in our group to run 2Ed, and even then, he didn't use kits. It took him years to try Forgotten Realms, and he ran precisely one DarkSun adventure.
So the Duskblade is out, and unless he's got it, so is the Dragonlance stuff.
Personally, I don't have Age of Mortals, just the basic book- I'm not a huge Dragonlance fan- but as I recall, he liked it more than I did. So its possible that he actually does have it...but not really likely.