Sofa contributed, but they are not "the founders" and this is not a "product" at all. Moreover they are moving because they have been acquired, so it has nothing to do with Appsterdam (apart of telling that this city is a fertile ground for good companies).
I don't think what you said had any sort of truth. Sofa has been purchased by another company, they are moving because they were bought not because they don't believe in Appsterdam.
The blog post linked in your grandparent showed that one developer left the company to stay, because they believed in Appsterdam. The implication is that other developers did not. Everyone made a choice here, including the owners of Sofa when they sold.
No, your logic is wrong, the implication is not that. It simply means that they chose Facebook offer because it made more sense for them, even though they totally believed in the initiative.
There is no logic implication that says otherwise and definitely is not in Mike's article, that is just an opinion of yours you are trying to support.
More on the subject on this post: http://mur.mu.rs/?p=156