This is philosophical, really. You're extremely likely to be infringing patents already. If Google sues Facebook over a patent, the likelihood that Facebook can counter-sue over patent infringements is extremely high whether Google uses React or not.

It's called mutually assured destruction for a reason. Stockpiling patents as deterence is the most reasonable thing you can do in a system that allows software patents. It's the only thing likely to keep others from suing you over bullshit patents.