I think you're quite confused on what constitutes a purchase. Money was exchanged for an item. The fact that they stated we could name our own price doesn't change that. Humble bundles work the same way. If these purchases aren't honored later, I'll be happy to never purchase anything they do again, leave negative feedback, and warn others to do the same.
Just to be sure, I've got screenshots of all the UI elements clearly stating that the game may be had by naming your own price, and it is described as owned in multiple places.