If the flier had flown straight and level out of the center maneuver drawing a line then rolled the airplane I would have zeroed the upcoming maneuver.

Reasoning,

The flier did indeed finish the center maneuver correctly, he only thought he didn't. Once he rolled the airplane he then convinced (me) the judge he wasn't sure he was correct for the up coming maneuver. If he had indeed been upright instead of inverted then the zero should have went to the center maneuver.

In my opinion once the flier has flown a straight line after a maneuver it's completed and all down grades from there on belong to the next maneuver. In this case a zero.

Tim