Paul says his game costs $16,000 to develop but has only brought in $84 in sales in it's first week after launch. He also says Microsoft has stated they will not help him with any promotional features or marketing in any way. He goes on to say Apple regularly promotes their apps, as does Android - so why won't Microsoft?
His overall theme to the post is questioning why Microsoft - who has few popular titles as of yet in their app store, won't promote such a popular game.
I think it's important here to understand that one week in the app store isn't long enough to gauge any kind of success, and Microsoft is constantly tuning it's store to better accommodate developers, unfortunately while some of their decisions seem to affect their #1 crowd (developers) I have a hunch it's all for the great good of the Windows app store.
UPDATE: Microsoft has decided to work with the developer to iron everything out :)