There's a pretty obvious solution to this: relicense React. The fact that Facebook isn't even considering that is a pretty strong indication that they "weaponized" their license on purpose.
> To this point, though, we haven't done a good job of explaining the reasons behind our BSD + Patents license.
I think we already understand the reasoning behind it.
> As our business has become successful, we've become a larger target for meritless patent litigation.
And the solution you chose stops merit-ful litigation as well.
> We respect third party IP, including patents, and expect others to respect our IP too.
Clearly you don't, because you've intentionally designed a license to allow you carte blanche to violate other companies' patents if they're dependent enough upon React to not be able to easily stop using it.