Thanks - I somehow managed not to look at that (saw it now after Twitter feedback). I can't edit my earlier comments so I'll just amend here instead: There are open source lawyers who consider simple permissive licenses such as Modified BSD and MIT to have an implicit patent grant. The first public discussion I found on this after a quick search is at http://lwn.net/Articles/389016/ - would love to see more and earlier.

If you the licensee also consider Modified BSD to have an implicit patent grant then the React patent grant is much worse for you than if it hadn't existed.

Guess I'm less less-informed now.