If you book a room that is part of a reserved block for a convention, it is not surprising that the organizers have discretion to kick out unregistered people in order to have room for legitimate attendees.
Flock, as the event organizers, had every right to revoke his registration, because he was not qualified, and what's truly remarkable is the volume of respondents who are shocked and outraged that Flock was granted control of the hotel rooms in a block which were dedicated and promised to their conference attendees. For crying out loud.
Just because you don't like the journalist, doesn't make them not be a journalist.
It's also hard to belief Flock is in the right here at all seeing how evil they act and what they sell to people.
Reading their email it seems like it was indeed under the event block. But the "called on my behalf" is a bit sus anyways.