"To keep Power constant (at 500mA) when the device has rigged current it is drawing so that it will get 1000mA, it COULD cut the voltage in half since it has control over that. BUT that violates USB standards. They specifically say you can't do that, your only response is to TURN OFF the supply of power entirely."
It's been a while since I read the specs, but isn't this statement contradicting how a USB DCP charger _should_ behave according to BC1.1/1.2 ?
As in, when Idcp goes above what the charger can deliver, Vchg should drop..
Now, Apples chargers are not DCP devices, but their phones/tablets surely know how to deal with a DCP charger..