The N4 was explicitly Google branded hardware with Google providing the hardware support (Google handled RMAs, component replacement, etc). It is Google's responsibility to support phones they sell as Google supported devices.
It is no different than when you buy a car. You go to a Ford dealership, they sell you a car, its their responsibility to repair and maintain your car during the agreed upon warranty period. You wouldn't tell someone to "file a ticket" with Ford instead of calling their dealer, would you?