From the article "Power users also authorized the software to send Facebook messages to other Facebook users for them"
So in your analogy. I created a business of sending snail mail to addresses I already had in my possession on my list of contacts. My contacts might not appreciate my snail mail, but I am not sending snail mail to the Facebook corporate Office -Or- if I am sending to the Facebook Corporate Office, then only though its mail routing department, which was set up to handle these very packages.
The C&D, I think, is equivalent to preventing contacts from communicating with each other, or, Postal Censorship[1], which I suppose is more a policy issue than a legal one. Which I suppose extends FB to be a governing body, which I guess leads us to CFAA...