That is ridiculous, and it shows the lack of economic understanding (that apparently many Indy Star commenters do have). If the Governor takes a trip for governmental business reasons, the trip itself is sunk for that purpose. It would be ridiculous to make State personnel pay for plane trips or "part" of trips ... what does that even mean? You want to start dividing miles into personal and governmental miles?
Do we make regular State personnel pay for going to see a movie by reducing their travel compensation after their business is concluded on a business trip? No we just assume they get their business done and THEN they do whatever private matters they might need/want to do on their own dime. I don't see how this situation is any different.