Here is a little history from Canada re bonding of Gas pipes. It was considered acceptable to allow the branch circuit bonding (EG) conductor to do the job. For example the gas furnace fan motor is a #14 with a #14 bond. Now enter a lightning strike and the bond conductor burns off and the voltage is high enough to damage the motor insulation causing leakage to ground. Since the bonding conductor is now burned off the O/C device does not trip and someone steps on a heat register and a grounded surface and gets shocked or worse. This did not just happen once, but enough to cause a change which requires a minimum #6 bonding conductor to the gas pipe.
So a little about lightning. Lightning follows the path of least impedance not lowest resistance. This is not necessarily along the copper ground wire but can jump from a lightning rod to a heat duct to a water line and into the building steel. the energy from a lightning strike has to dissipate and can travel horizontaly over a wide area around the ground strike. It can just as easily follow a gas pipe into the house and cause havok to the interior wiring. In my jurisdiction the gas piping is plastic in the ground and the meter has an isolated section too.
