I don't see how this makes everything okay to use now? To me it basically means, if I sue Facebook for any reason involving patents, I would have to give up us

I don't see how this makes everything okay to use now? To me it basically means, if I sue Facebook for any reason involving patents, I would have to give up using its code. I invent a time machine, Facebook can infringe on my patent and I can't sue unless I stop using their code. Please tell me I am wrong.