I don't think "pick your battles" is quite fair. I didn't read this as him being stubborn for no reason, at least not in this initial message. He knows Facebook

I don't think "pick your battles" is quite fair. I didn't read this as him being stubborn for no reason, at least not in this initial message. He knows Facebook has a reputation as a strong technical team, and since he is applying for a technical job, he probably thought they'd appreciate the attention to detail of giving a thorough response. But yes, it certainly is a lesson in dealing with nonsense.