Because there are a lot of leftover beers from the Final Round, the organizers make sure it is put out following the Awards Ceremony; otherwise they have to haul it back home and figure out what to do with it.
You're right, there were a lot of leftovers in Seattle because last year the number of competitions went from 10 to 11. With 10 competitions there are 840 possible entries in the Final Round, and for the previous 3 or 4 years, only 760 were actually submitted to the Final Round. With 11 competitions there are 924 possible entries, and last year 871 were actually submitted. That's an increase of 111 entries, so 333 additional bottles.