It has been updated for Intel. Although MacSoft had to totally rewrite the game to do it, so they charged $5 for the patch. Unfortunately they don't have the rights anymore so you can't buy it, but if you do some googling...
What a shame. You're right, there
is a fully working Intel version that works just fine in 10.8.4. But since there are no laws that force anyone to sell a product that already exists and was once sold, even if it costs nothing to the seller, I guess you'll never see it for sale again (well, I can imagine M$ selling it on the iPad easier than on the Mac).
Heck, Microsoft bought Bungie and didn't even let them release the working versions they already had for Windows and the Mac at the time and didn't release them for two more YEARS for no reason other than to push their stupid XBox system. It's like Microsoft refusing to upgrade DirectX/3D for Windows7 in order to PUSH Windows8, even though MOST Windows7 users don't like the Windows8 interface and would rather keep Windows7 (and XP versus Vista before that).
Personally, I wish they'd leave gaming out of these OS war type things. I realize a company shouldn't have to support an older operating system forever, but ignoring what the public wants (whether it be Apple pushing this new Mac Pro design on people that need expansion ports or Microsoft trying to cram Vista down people's throats in the past and to some extent Windows8 now), it's just petty crap that makes me hate the companies involved even more. But I guess they don't care if you hate them so long as you keep buying their crap (seeing as Linux doesn't post any kind of threat to either company's operating systems...well maybe Android does, but until Google goes desktop or console, it's kind of moot for gaming, IMO).