It doesn't need to say that. The code is not meant to make electricity completely harmless to humans. It's meant to prevent common injuries. Dismounting equipment and pouring water inside the equipment is not something that would be common.The code most definitely does not say that it isn't required if your equipment has built in GFCI protection.. that does not protect you from mounting and raceways or dripping water inside your hardwired connection .. it only protects you downstream of the equipment very similar to the UMC
The enclosure is weatherproof and rated for outdoor use. The requirement is designed to protect people and not equipment or property.
You seem very passionate and have taken a lot of time to look into this. Like I said though it meets code. Code requires GFCI protection and it has it.
Nothing more to really say on this.