It is because right now, the options for him in the digital world are not to his liking.
Alpha, I'd say hold out for a short time and don't jump the gun. Yes they may be rumors but there is a *very* good chance that Nikon is coming out with a 20+ MP camera in the near future. The thing that you need to be aware of, is that traditionally, it is $1000US higher than the model beneath it.
So, if something like the D3x (or whatever they name it), comes out, it will be in the 24 MP range and also in the $5500-$6000 range. If that is out of your price range, you are always back to a D3 or D700 as choices.
I sincerely feel that even at 12 MP it is more than able to meet your expectations. After all, you are wanting to expand your business line, right? That means that clients other than those needing billboard sized prints will be knocking at your door and their needs should coincide with the capabilities of a D3. It really is the best camera out there at this time, bar none.
However, a D3x sure looks to be the camera of your dreams at this point. Close the wallet for a while and wait, that is what I think is your best solution... unless you tell us that you need to do this tomorrow. Then I suggest you bite the bullet and go D3.
As for lenses, you have all the choices from the 1970's to present to choose from, all manual focus capable and some incredible lenses in that range to boot. Don't forget to check out some Zeiss lenses too. I hear they are ok (lol).
Feel free to put me on iggy for sharing my opinion, I don't care.