[Dave...]

I believe that rule <G10> is that the human player cannot stand on someone else's shoulders, bring a stepstool, etc. Clarification from FIRST is probably needed though.

Since it falls under the "SAFETY" category, they don't want someone getting hurt by falling. Handing a ball between players doesn't seem to pose a safety risk, so not allowing the balls to be passed to other team members is most likely not the intent.