[prewett]

> any developer contributing ... has a moral obligation to stop

Oh, come off it!

If you went to some company and got a patent license, and then proceeded to sue that company for patent infringement on an unrelated patent, they would terminate your license. (That's what cross licensing prevents.) So FB is granting React users a patent license free. Why wouldn't they revoke the license if you were suing them? There's no difference from the normal state of affairs except the patent license is free. Now, if you are worried about FB infringing on your patents, it's wisest not to use React, but that's no different than licensing a patent from someone else.