No, any question related to development is not on topic here. This site is for questions regarding a problem you have on your phone. Development related, like in that post, is not in scope.
Questions on how the marketplace works are 100% welcome. However, IMO the question you linked to, (and this the one that would set the precedent here) would get closed almost immediately. It isn't just from the perspective of a developer, but a problem about developing on the phone. If the question was 'I am working on an app, and it is going to be very content heavy. What is the max size an app can be to be able to be downloaded over 3G' even though that is from a developers view, that would be OK.
What makes it OK is that the actual question is about the marketplace restrictions. not how to code around them
I am aware that this type of question is ok on android.se, but as of now it is not ok here. Where would we draw the line?