sadly, there is a TON of misinformation on any supplements that have association with muscle-growth, libido, and/or diet aids.
I can't say i know for sure that's why i was curious, but generally speaking the body has no trouble digesting what amounts to half a cup of milk's worth of protein (4g), regardless of what it's consumed with. And, generally speaking again, simple sugars tend to increase absorption of the macronutrients because of the insulin spike they create (insulin is an incredibly anabolic hormone and does a great job shuttling everything from protein to creatine to muscles after workouts, hence so many super-sugared(or maltodextrin, which is just less-sweet sugar) post-workout products.
i wouldn't be surprised to find that all of their claims re "absorption" / "effect" being dependent on their conditions are, in fact, veiled attempts to get you to simply use it in a manner where you'd see/feel it more noticably (ie, it hits you quicker on an empty stomach- ergo you perceive it as more pronounced than if it kicked in a lil slower - ergo you're more likely to stay on the product. This wouldn't mean a full stomach was inferior - it could be quite superior but just not as much of a 'kick'(think of caffeine in this regard, yknow?))