Peacock and Data Usage

Regarding the "free" Peacock app available to Comcast customers, it is considered "Internet streaming", even though the service is ported through a set-top box, right?  We've disconnected our  "smart" HD TV from the Net for security purposes, so any streaming that comes through a Comcast app must 

be via coax, and NOT the house modem/router, is this correct?  We're making sure that we stay on top of Data Usage, and trying to account for every device that may carry an Internet signal to the television, wittingly or otherwise.