Given that software patents probably shouldn't even be allowed, I'm okay with this. Also, it's not THAT different from the fairly popular Apache License 2.0's patent provisions.
Sorry but I think you are quite mistaken regarding Apache 2.0 - that termination clause is only triggered by patent claims relating to the "work" (i.e. the derivative software) whereas the React licence appears to cover any claims made against FB. It is a big difference!
I agree that software patents should not be allowed and am fortunate to live in a mostly sane jurisdiction where they are mostly not allowed but that's not the case for everyone.
Who said anything about software? Facebook or one of its affiliates could infringe a hardware invention and suing them for it would have the exact same implications.
I do think that the VAST majority of patents should never have been, or be granted in the first place... I do feel that there is some place for them, but very little is done that isn't so completely derivative, that it deserves them.
