Additionally, I almost brought this up in my original post, but decided against it, but "lawful content" is another phrase I commonly see in the same discussions. IANAL, but my understanding is that unlawful != illegal. "Lawful" means the subject is specifically addressed and permitted by law, and "unlawful" is anything else. So traffic can be legal, but not lawful.
My biggest fear is that we in the tech community will rally behind a net neutrality law which sounds good in theory, but ends up a nightmare in practice. Phrases like "ISPs will not be able to filter lawful content" are nowhere close to "ISPs will not be able to filter traffic". I'd much prefer the latter in a net neutrality law.