There is really no talking to that guy. He thinks that being on the platform and hosting your own content means you owe Apple money when you allow people to purchase from your servers. Even Apple dont believe that any more.
Heres a trick - the app can now show its website internally. Of course that is not what they want.
The other common viewpoint, and one that Apple tried to use to justrify the old policy and their 30% cut, is that iDevices add value to the apps by making them possible; but then they completely ignore the fact that the apps add value to the iDevices so people will buy them in the first place. It's a two-way street but Apple tried to make it a one-way toll booth.
Now the customers can decide if the extra convenience of in-app purchasing is worth a higher price (because let's face it, no publisher is going to charge a higher price on their own web site than it is on iTunes). Apple dictating the prices they charge on their own web site based on Apple's markup was always wrong.