I doubt they're acting maliciously too, but it's not as rosy as you paint either. The patent grant is automatically lost if you argue "any right in any patent

I doubt they're acting maliciously too, but it's not as rosy as you paint either. The patent grant is automatically lost if you argue "any right in any patent claim of Facebook is invalid or unenforceable". Notably, this applies to all patent suits, whether or not you're right, even if you're the person being sued, rather than you vice versa. In effect, Facebook can revoke the patent grant at will just by bringing an onerous patent lawsuit - you can either agree to their arbitrary terms (e.g. never to use React again and pay X billion), or you can argue their patent rights are invalid or unenforcable and lose the patent grant. That onerous suit might be over the very patents this grant licenses; it really doesn't matter. At best, this is a promise not to consider past patent infringement, since you'll receive warning that your license to React patents revoked. The fact that suing over usage of OSS would damage their reputation is irrelevant: even without a patent grant it would be perceived as extremely untrustworthy to sue over submarine patents. The patent grant doesn't really change that (it might make the commentary even more snarky should such an event occur, but that's about all). Also, realize that if this ever does occur, it's unlikely to be in a world that looks at Facebook like it does today. This is typically something you'd expect of a company in decline: they're not after good PR at that point, but after extracting maximal rents from others. And of course it wouldn't need to be Facebook itself that filed the lawsuits; they might sell off that intellectual property to some patent troll and claim (somewhat reasonably, I might add) that it's not really their responsibility what happens later on. Actual events have repeatedly shown that large firms have no qualms in making somewhat shady IP deals if that can give them a competitive advantage (e.g. the lawsuits surrounding android). In short: I don't think bad PR is a very effective disincentive for a patent lawsuit.