In going through the updates and adding them to
HyperRules, I have to agree with Jason Morella on this one. The only rule which FIRST has changed regarding an opponent holding a container is
SC8, which ONLY deals with which containers you get one point for. Nowhere in SC8 does it discuss the multiplier. Rather, the multiplier is discussed in
SC9, which has not been updated regarding opponents holding containers.
Something to keep in mind that I just realized as writing this is nowhere in
SC8,
SC9, or
SC10 (the rules regarding scoring) does it state that measuring will be done from the ground. Therefore, it may be the case(we'll have to wait for clarification on this from FIRST) that in the event that the largest(I'm not using the word "tallest" here on purpose) stack is being held by an opponent robot, it may be measured from the bottom of the lowest container in the stack.