Normally a USB port should have some sort of overcurrent protection and should provide up to 500mA regularly. The iThings implement a special “protocol” (some resistors, to be specific) to handshake with the host (in this case the Qu) for more current (faster recharge).
If designed properly (which I somewhat expect from A&H) it should not be a problem to connect an iThing for charging.
There are several spinning HDDs around which pull more than the allowed 500mA from the USB port and the Qu nicely deals also with those.
I personally won’t fear to misuse the QuDrive-Port for charging, but some official comment would be nice though.