Nope. Not the same principle.
Marriott's were spanked for mis-using the spectrum by deliberately making it unusable. Right up FCC's alley and very cane-worthy.
Here they were asking people not to use other WiFi. Private property and entry by agreement with T&Cs only. It is likely within their rights to do this.
I still think they are greedy unprintables, though.
It was ruled that it was against the law to jam wi-fi signals, but that doesn't necessarily stop them from enforcing their T&Cs (which the attendees agreed to) and throwing people out who are breaking them.
Incidentally, I do wonder if the same would be true of an attendee using bluetooth or USB tethering, or a USB dongle. In my mind, stopping people from using their own wi-fi hotspot can be justified. I have seen first hand (at a trade show) how much it sucks when everyone sets up their own wi-fi: They all overlap with each other, and none of them work, even the venue's, so they are protecting the quality of service of their own infrastructure by banning it. However, using BT/USB tethering should not* interfere with the venue-provided service, so there is no such justification and it would just be pure gouging.
* I am aware BT and wi-fi both use the 2.4GHz band, but am yet to see an instance where BT has interfered with wi-fi. If I'm wrong, I'm happy to be corrected.