For what it's worth, here's my assessment:
First off, and no disrespect to Zonta, Bourdais is a very good driver. Usually his name seems to come up a couple times in the off-season as a candidate for a seat somewhere. In short, Bourdais is probably the better driver given similar equipment.
Second, the Toyota set the record during the Monterrey Historical Races, if I remember correctly, whereas the new record was set during a CCWS test. Zonta's statements afterward seem to indicate that he could have gone faster (from formula1.com -
http://www.formula1.com/news/4819.html):
"The older cars dropped oil in places on the track and I didn't want to challenge the car because I couldn't be certain where the oil was,” remarked Zonta. “I needed to assume there was a high possibility that oil was in many places. It was also more windy today than before and the blowing dust made the track slippery in places."
and:
"We put slicks on after the installation lap, but the sun came out later today and the track didn't heat like it did the last several days," he added. "Unfortunately, the tyres couldn't work as well as possible."
Third, and again no disrespect meant, Toyota was not exactly the fastest last year. I am not saying that another team would hae gone faster, I just think there would be less of a grey area here if it were the Renault or Ferrari setting the previous record.
In any event, this is not meant to take away from Bourdais' accomplishment. I enjoy watching the CCWS, and this seems to be a step toward making the cars faster and the racing more entertaining. So congrats to both Bourdais and the CCWS, it looks like they have a winner with the new Panoz chassis.