Now where does it say that? The way I read it, so long as you don't sue Facebook, you have a patent grant. If you believe people when they say that their patent portfolios are purely defensive, there is no problem.

On the other hand, being the aggressor in a patent lawsuit loses you the patent grant. This seems sane enough to me.

The normal state of affairs is completely ambiguous about patents. You get no explicit grant, so if they feel like suing, there's nothing to stop them. Some people claim an implicit grant, but there's no conclusive ruling on it.

I don't particularly care for software patents, but I don't see anything more stupid than the usual lawyerly CYA layered on an attempt to disambiguate the patent situation.