I suspect the “BBB” abbreviation for bulk-only-Transport is intended to contrast with “CBI” - Bulk/Bulk/Bulk vs. Control/Bulk/Interrupt.
I never quite worked out what the UAS host controller support was about but I got the impression it was something Windows specific. Something about the UAS driver only being enabled if the driver for the USB host controller’s driver explicitly allowed it or something along those lines, and only in the earliest version of Windows that supported UAS. But I never bothered to fully track this down. It could also just be someone in the standardisation -> HW impl -> SW impl -> Marketing either misunderstanding something or just making things up.