I certainly can’t say for sure. Using “i.e.” would mean they must be on a Mobile Goal. But far too many people mix up “i.e.” and “e.g.” It could well be that the two got mixed up and that transporting stacked cones without a mobile goal is fine. That error is especially likely with the way “Stacked Cones” don’t count and the same “Stacked Cones” can be on a Mobile Goal. But at the moment that use of “i.e.” means the rule specifically allows only Stacked Cones on a Mobile Goal.
The definition of stacked seems to indicate that it must be on a goal. Cones are only “stacked” if they are stacked on top of other “stacked” cones. The only other way a cone can be “stacked” is if it is fully nested on a goal. Therefore stacking multiple cones on top of each other while they are not on top of a goal would mean that none of the cones would be officially “stacked”, and you would break sg9 by possessing them.
It seems that cones are considered “stacked” if and only if they are fully nested on a goal or another stacked cone. So a “tower” of cones not on a goal is not considered a “stack” and cannot be possessed by a robot.
Could a robot possess a stack of cones and an individual cone at the same time? For example, could a bot carry a moveable goal with cones on it and load more cones on while still possessing the goal?