I am aware of some organizations that negotiate a deal with the hotel whereby they get the meeting rooms for free, and the hotel rolls the fee into the rate they charge for the blocked sleeping rooms. Hence, in some cases I have been able to get a better rate through the hotel web site or an OLTA as a regular reservation, bypassing the room block for the convention.
In the case here, it sounds like Passkey is paying a kickback to the convention sponsor for exclusive rights to the room block.