Pretty sure that's from the writer. Ayre have not made much of the 24/96 angle as Charles Hansen seems much more interested in handling jitter better through the use of asynchronous mode. The rationale behind the QB-9 is laid out here:
http://www.ayre.com/pdf/Ayre_USB_DAC_White_Paper.pdf
Regarding USB limitations, I see that the paper says:
It appears to suggest that parallel use of the TAS1020B with custom drivers is required to get around that limitation, though I have no idea if this is the only way or indeed even if the limitation extends to other common USB chips.