Filing gets you nothing, he has to win the suit which will be really tricky because he didn't spell it out on paper first. Even then what does he have? Less money and no product. Not to mention looking extraordinarily incompetent in front of the public. Simply having a contract in place would have made this cut and dry.

Filing may get them nothing, but he can get an injunction that prevents FG from launching the product and thus getting funding for a coming legal battle. I bet the shortage of money would make them more amenable to Arrington's allegations of who owns the IP...

Looks increasingly like MA found some company who could develop a product and that could be bullied out of the deal when it's ready to be taken away.