Bob,
I am curious to why you would apply the NEC to a UL listed piece of equipment?
Just because a product is listed doesn't mean that is in compliance with the NEC. In my opinion, any connection to the generator, either hard wired or cord and plug connected, is premises wiring and this wiring must originate from a grounded system. If there is no internal bonding jumper, it is not a grounded system and you can't use the power from that system and be in compliance with the NEC.
That being said, I think that in most cases, an unbonded generator is safer than a bonded one.
Don
