Wrongo.
Him being the sole owner of the property can simply release the code under the GPL and use Apple's license for the Store's binaries.
There are no GPL'ed apps. There is GPL'ed code. Owners of the code can decide to do multiple licenses depending on what they want to do with it.
If I make an app I can make it GPL and then keep on developing it myself and after a ton of changes release a proprietary app and then another ton of changes and that third version of the code make it GPL as well and at the same time put the binary up on a place like the App Store and at the same time put the code somewhere else with a BSD license and then again somewhere else post it as public domain.
It'd be a silly thing to do, but as the owner of the property its your prerogative what you do with it.
This silliness about the GPL and the Store needs to stop. It's misinformation all-round. A different thing is that you can't take someone's GPL code and build an App Store app with it (unless you get permission and a special license from all owners of the copyright).
As for Objective-C it works for other platforms and if he actually prefers just Cocoa he still has OS X as a potential platform (plus whatever Apple decides to incorporate in the future, if they ever expand). Your main career goal as a developer should be making a living developing and, ideally, make boatloads of cash. Painting yourself into a corner may, if anything, be bad strategy; but only if it hinders that objective.
Posts like these are not good because they're misinformed and spread misinformation. They transfer blame so they do nothing to assuage the actual problems:
1.-People who plan on making a living developing should have a backup plan. It may not be as easy as they think.
2.-People who plan on making a living developing and are smart about having a backup plan should first "test the waters" before they go full-blown corporate. Develop and release some apps as an individual. See how they behave. Especially if they're your first apps after learning the language and the platform.
3.-Setting up companies is hard and tests everyone's patience. This needs to be ACCEPTED. No matter what your rush, the bureaucracy walks at its own glacial pace. Better understand it early. Also: Frustration shouldn't equal anger.
4.-Document yourself. DUNS is an industry-standard. It's a horrible one and they are scammy and artifically bureaucratic (so they can sell you the shortcuts) but the requirement it's been there for a while and there's plenty of information on how to make it less painful.
5.-Learn where to put blame and focus your frustration. Ask around and find shortcuts and workarounds. DUNS is not Apple and while Apple's requirement of DUNS is frustrating it has its reasons. If selling in the store makes sense to you financially then wait out the free registration from DUNS or decide to pay to get it faster.
If patience is not your virtue you might not be shaped to be an entrepeneur anyway, so Eduardodm should thank DUNS from helping him get out early, as this is nothing compared to what was yet to come.