well, there are exceptions its true. and really, if an app is very good and already successful then they will feature it - the problem is that the success of an app can depend on early features. angry birds will be featured because its already successful - if they don't feature it something is obviously amiss.

i don't really have any great concrete sources i'm afraid, its not documented and aside from the web articles i assume you already easily found with google from my prior comment, it comes from hearsay at the pub from talking to other gamedevs and from at least one meeting with apple employees where everything discussed was NDA although i'm sure i can say that such a meeting took place. although the idea that they suggested not shipping on android for at least a few weeks after launch on ios shouldn't be too far fetched...

the fact that not mentioning other platforms in metadata is a submission requirement is a very strong hint too. its an unreasonable request however you cut it.

i despise legal gagging of this kind - i consider it thoroughly despicable and cowardly - only necessary when you know you are in the wrong and don't want anyone to find out, or are deluded into thinking that your corporate secret isn't better off in the wild where it can benefit all of humanity - i.e that you are more important than everyone else and somehow deserve a reward for acquiring knowledge or keeping secrets.

there is also a bit of 'i am going to ship something in the near future'. i've already said more than enough to do damage to myself here. :)

as i hinted at in my initial response this 'idea' is easy to uncover if you do the usual research anyone would do before shipping. (google)

EDIT: okay so not sure how i forgot this because /i worked there/ but when apple ran their 'stargazing app' promotions about a year ago they only featured ios exclusive apps - they also were regularly featuring starwalk aside from that promotion (which is ios exclusive). the app i worked on 'star chart' was not featured - it has been featured recently because it early adopted the iOS 7 UI style - but before that it got missed despite outranking most of those other apps and being a higher quality product more consistent with apple's design guidelines and ethos. now i don't think that necessarily the app was worthy of feature, but a lot of much less polished or worthy apps got a lot of screenspace on the store and the only thing they had in common was not having shipped on other platforms. as much as i dislike those guys for their disgusting attitude towards customers and employees - frankly they deserved better treatment than they got from apple in that regard. not being featured is fine, but featuring vastly inferior competitiors because they are exclusive is utterly despicable.