I don't think they're doing this to save money on Comcast bills
They're probably allowed to use separate devices (i.e. sans corporate credentials) to access the outside web when they need to look up specs, SO questions, etc. This is just about air gapping critical systems.
I really have no idea why this is even a news item worth reporting, and jumping at the opportunity to criticize Google for this is a bit of a knee jerk HN reaction imo.