I don't see having an exclusive platform as an advantage right now. If they could pull off iOS API compatibility, that would be brilliant (assuming their patent cross licensing with Apple adequately covered their asses) and could be conceivably be done starting with GNUStep, but Android seems a good second-best option.

OTOH, I believe the Apple app store TOS would prohibit any in-store app to be distributed in any way other than the store, so, there is one interesting contractual risk.