I always liked the language about using the EGC of the circuit likely to energicze the piping. That is usually accomplished in the design of the product. Trust but verify is my motto tho.
We did a bunch of those gas space heaters in state projects and I had one on the ground that they let me look over before the install. They had a bonding terminal for the EGC that was solidly connected via the internal metal parts to the pipe hub. Made up gas tight this is a good bonding path.
