I think the move to open-source the code was a ham-fisted way to get the "we're modifying copyrighted documents in flight" part past the lawyers. It's admittedly a pretty decent legal move.
He is mistaken, it has nothing to do with it. My code is included in Comcast's injected code, but that doesn't mean any of Comcast's liability has shifted to me.
I don't get it, how does that work?