Drift, breaking the rules anywhere is not a good thing to promote, work in it or not. The Origins Convention is a pay event, and that it will stay. Telling someone "you can get away with it by..." is bending/breaking the rules...
So unless they feel like sitting in the food court the entire time and not getting up, I would suggest they buy the Parent Badge.
Purchasing the badge also keeps the convention that we love oh-so-much running. So if nothing else, at least help support GAMA in their future of bringing us Origins.