Shouldn't exit poll stats be final soon after the polls close -- in the same way that pre-season predictions are "final" once the season begins? The AP quote sounds like a kind of CYA-move re: possible hanky-panky with the votes.
From an explanation of exit polls [here]:
Once the polls close, the interviewer will attempt to obtain actual turnout counts, and if possible, actual vote returns for their precinct. One of the unique aspects of the exit poll design is the way it gradually incorporates real turnout and vote data as it becomes available once the polls close.I'm not sure what this means or how it is done.