Perhaps you recall an incident last year at the Monsoon Cup involving this very specific issue? (If not go to: Equipment in normal position? a blogpost explaining the situation in detail with photo's)
Before we can go to the Rapid Response Call, we have to look at CALL UMP 18 from the Callbook:
CALL UMP 18:
Rule C2.1 Changes to the Definitions - definition Finish
Definitions Clear Astern and Clear Ahead; Overlap
At a close downwind finish, Yellow eases her spinnaker halyard, sheet and guy so that the sail is further ahead of her bow than normally. When does she finish? What action should the umpires take?Answer
Yellow finishes when her bow crosses the line. The definition Finish makes it clear that as the spinnaker is not in normal position it cannot be considered for the purpose of finishing.
Judging the finish is solely a matter for the race committee. However, if the umpires see the halyard eased they may advise the race committee, since the umpires may be in a better position to see the spinnaker before the boat crosses the finishing line.
The same reasoning would apply when two boats approach a leeward mark and there is a question about whether they are overlapped.
And now to the RR CALL 2009/002:
The situation is the same as in Call UMP 18.
Would the answer be different if Yellow was in the process of taking down the spinnaker?
No. A spinnaker in the process of being set or taken down is not "equipment in normal position" in the context of the definitions where this term is used.
We can all argue until we are blue in the face agreeing or disagreeing with the answer. But that's precisely why Rapid Response Calls are published; so we at least answer all the same, consistently.