If I was designing a light fixture with a built-in HomePlug-wireless AP; I would use a wiring design that allows the light to be independently switched from the AP. It will then allow the AP to continue to provide wireless service to the area whether you switch the light on or off.
This may involve a switching spur that is wired in series to the lamp socket, with the AP wired in parallel at first point. Then a wall switch is wired over the switching terminals. If the AP circuitry is in "short-form"; as in a commercial design, this would allow the circuit to be "designed" in to the fixture; therefore allowing for electrical-safety compliance and flexibility with light globes.