I have a sneaking suspicion that he was referring to people bringing their own tires for this weekend of practice, not for Worlds. In other words, they have 1600 sets ready, but since people are bringing their own sets now for practice, they can't tell how many sets will be consumed (and thus how many will need to be ordered for Worlds to restock.)
Maybe I am wrong, but this makes a lot more sense than allowing folks to bring their own tires!
EDIT: I am not disagreeing that communication has been horrible for this event, but I think a lot is getting lost via really poorly worded facebook and rctech posts. The facebook post about ordering tires through Superior was absolutely absurd.