I think none of this is relevant, it's pretty clear Arment personally doesn't believe that anyone can make an 'Android Instapaper' with the same quality, features, and level of support, running on enough compatible devices and sold through enough Android marketplaces, to make it _as profitable_ as just concentrating on iOS and be done with it.

The challenge he puts forward is for someone who disagrees to take up. Personally, looking at the Android ecosystem and the quality of applications in the Android Marketplace, I think he's right. It's perfectly possible to write great Android apps, and many exist, but if you look at who makes them, they are without exception applications made by big corporations who don't make money off the apps themselves, but from associated services, ads, etc.