Another thing that makes this legal is that a user can become like a ISP, just passing packets.
ISP's have not been held liable for content they "pass through" because they are just like the phone company and just supply a means to pass packet data.
So who's to say a user can't become a mini ISP?
Where does your ISP stop? What if your part of the ISPs system includes passing packets when you get a "signal" from your ISPs TCP/IP sent packet?