Are you nitpicking legal semantics (including something in one agreement or another), or saying it's possible to legally use React-Native while suing Facebook for completely unrelated patent infringement?
It is absolutely possible to legally use React while going ahead and suing Facebook. You do not lose your license to React by suing Facebook.
What you do lose is an explicit grant of additional patent rights - the grant given in the PATENTS file. Note that there is no specification therein regarding what patents might be covered; it's completely possible that none of Facebook's patents have anything to do with React. I haven't looked. in any case, patents are totally distinct from you license to use React.
OK, so I can legally use React-Native in my app while suing Facebook for unrelated patent infringement. I also can claim the patent they are suing me for infringing is invalid while continuing to use React-Native.
You have to differentiate between copyright and patents.
From the perspective of copyright you're perfectly in the clear, the grant of rights that's part of the BSD license will not be revoked.
What will be revoked is the right to Facebook's patents insofar they apply to React.js. First of all that that requires, that Facebook actually has patents that apply to React.js. It also means you're no worse off than without a patent grant.
I prefer the Apache 2.0 wording, but this seems to be blown widely out of proportion.
