I really don’t want to pick a fight with the IAEI, but IMO, if the electrical equipment and wiring attached to the metal siding is properly installed, then "likely to become energized" is for all intents and purposes, a moot point.
The listed equipment, boxes and enclosures that are mounted directly to the siding, when properly installed in accordance the NEC and the manufacturers listed instructions, are bonded to the equipment-grounding conductor of the branch circuit or circuits likely to energize it through listed means, meaning grounding screws, lugs, etc.
All of the shock hazards that I have seen or heard of where energized metal siding was involved, were the direct result of either improper installation or a screw being driven into a wire inside a wall that was not part of a circuit likely to energize the metal siding.
