I agree that it is helpful to point out that there are major risks when you develop for an alleged platform. But isn't that the point of his post?
I think the point of the app.net initiative is to create a platform that because of its different business model (subscription for infrastructure/service) will not suffer the conflicts that are inevitable when the business model is ads. And whilst this is indeed unusual lately, it is not long ago that such for-profit platforms were the norm. Older examples include, DOS, Windows, UNIX, Linux, X-Windows... More recently there is a profusion of companies providing commercial support for open source software or providing such software as a service.