It would be nice if a first hand app developer would be able to chime in. I can only guess but my thinking is.
Step 1) An app developer programs something targeted for iPhone5 or SGS3 first and let's say that takes the same time.
Step 2) How long will it take to revalidate it for 4S/4 vs (the next top two phones for Android)
What income or market/time involved will they get between iOS vs Android in step 1?
What income or market/time involved will they get from going to step 2?
That's the only reason why I think iOS is prioritized. They can get the most $$$ per development time at first and then work on expanding to Android. But this is me just making stuff up.