If there is a boat to windward of you, not moving on the starting line, is it legal to push your sail out and skull (making sure your tiller does not cross the mid-point of the boat) to make your boat move sideways, and get closer to the competitors boat, essentially cutting off the room they had to leeward?
Keep in mind, the actual technique is legal, as you are allowed to skull as long as the tiller stays on one side of the boat, but would the leeward boat still retain rights if they were doing this?
Please share thoughts and opinions, as well as references from the RRS
Not really. It isn't legal. Sculling as defined in the RRS is "repeated movement of the helm that is forceful." You can only scull to move from head to wind down to closehauled (rule 42.3(d)) so really it is sculling.
which says nothing about whether or not the tiller moves across the centerline (which is an old definition). The ONLY exception is that IF you are ABOVE a close-hauled course then, subject to not propelling the boat forward, you may scull down to a close hauled course.