So opensource it all right now. If Fusion Garage plans to sell it on their own anyway then release all the specs and software so that anyone can build one themselves.
(Also, I think open source hardware contains a fundamental contradiction: "anyone can build one themselves" goes against the economy of scale you need to get reasonable production costs.)
If they both have ownership rights, as Mike says in the article, then they can both decide how to use them. Fusion Garage has decided to use them to produce the Tablet on their own and TechCrunch has decided to opensource it and allow any manufacturer to produce them.