If the app is closed , there are no ads being displayed hence no revenues for Dan. If Dan is displaying the main site ads without using Apple's iAd network, then how is that any different than just viewing the site through a mobile browser?
I agree with you that using the forums on mobile is annoying, but I don't think that investing money in an app in the solution. A good mobile-optimized site is more than enough.
My opinion. DD.com and DDF are purely informational, i.e. you are just reading and writing. You don't need access to the camera, the microphone, the GPS chip, the accelerometer, or any of the hardware capabilities that would require a native app to function properly. Everything you do on DDF can be accomplished in a mobile browser. Apps are all the rage at the moment so everybody and their uncle thinks "We need an app." You don't.
Besides, developing a quality app for both iOS and Android would cost a minimum of $100,000, plus updates and support.