I'm sure Eric or someone else from NAQT will
state this more clearly than I can, but the way I
understand it, that's why they play six rounds of Swiss
pairing after the six original rounds. All the top teams
_should_ play each other, and IIRC from my 1998 ICT
experience, you needed a record of just 9-3 to finish in the
top six.
Perhaps there is a way for a team
with three losses to get shut out of the top six, but
I doubt there's any way for a team with even two
losses to suffer that fate.
-Adam