This scenario's premise assumes Expo's success could heavily depend on claiming patent infringement against Facebook. If that were true then it'd probably be simpler not to use Facebook open source under the BSD+Patents license.

But for several reasons, the Expo team is working without the assumption we need the option of suing Facebook for patent infringement to be successful. I find companies that are sufficiently durable for other reasons to be more appealing to people whose livelihoods depend on the company in some way, including developers, the team, and investors.