Well, someone from Mediacom allegedly did say it was a "mistake" earlier when this story first broke:
said by pokesph:
data interception and modification.. bad, very bad.
After talking with Mediacom's Legal dept, (Tom Larsen) they are in the process of disabling this 'service' and say it was a "mistake" by the marketing dept and never cleared their legal dept lawyers.
If it is still happening, you can contact Tom at 1-888-692-9090 x2754 and tell him so.