So you approach this contract as "I can only do what they tell me I can do" That reference is clearly permitting the user to have multiple devices share the Service, but only under one IP address. It also tries to limit data sharing withing the "home" (not defined).
The reality is that Verizon cannot control what happens when the data leaves their lines. If you hook up an wireless router to your modem, Verizon cannot actually restrict who connects to your router. It is your router and it is the only one using the Service. You can still be following the TOS and allowing piggy backing.
Also, this means that either you cannot take your computer out of your house or it means that your friend cannot use it when he comes over....depending on your definition of HOME.
They may TELL you that your are in violation and anything past the router is using the SERVICE, but you could TELL them that you aren't. Then they kick you off, so I guess they would win.