RYA Winter Challenge Act 4 (2)

UPDATE: Regatta report on the RYA site: Green wins chance to defend Winter Challenge crown.
As promised a post about the Match Racing at Queen Mary Sailing Club last weekend. This was act 4 in the RYA Winter Challenge. We had a great weekend with very good sailing conditions on the Queen Mary Reservoir. With my brand new digital camera I took some pictures and if you are interested, you can see them all on Flickr. Go Here
Please excuse the lack of professionalism in my photos and leave me some room for improvement.As for any rules issues, I'm always amazed that each event seems to bring something new. This time it involved a couple of questions about an incident on the finishing line. Let me first tell you about the incident:
In the final run of a match, two boats separated about half way down the leg. At about 6 or 7 boat lengths before the finish they came together again and after both gybed a couple of times ended up with Yellow clear ahead and Blue clear astern entering the two BL-zone. The distance was however minimal. In the 2BL- zone the spinnaker of the trailing boat sometimes overlapped the front boat and then, a few seconds later, did not. After Yellow crossed the finish, her crew started to prepare to pull down the spinnaker. She luffed slightly. Blue, who was trailing her, within a distance of less than a meter, preliminary wanted to pass to windward, decided, after seeing that slight luff, to go to leeward. By that time Yellow had cleared the finish line completely and her spinnaker was no longer pulling. Just after Blue crossed the finish line, but not yet cleared the line, there was contact between the bow of Blue and the starboard side of the tiller of Yellow.
Blue kept her spinnaker full and ran into Yellow. There was damage, which later was estimated to exceed repair costs of more than a 100 pounds.

Together with another umpire I was following this match. We waited for a call from either boat. It did come, but - in our opinion - much to late. It took Yellow about 30 seconds and came after the spinnaker was lowered completely and she was close hauled. The Yankee flag was hoisted together with a red flag, indicating a red-flag protest by Yellow.

We did the protest hearing after racing on shore and under RRS 14 the PC decided that the trailing boat was the only one who could have prevented the collision and she was penalized with half a point in her results.
I've captured the incident in a TSS-diagram:









And here's the download link to the original TSS-file: UMP_LTW004.tss
Talking with the helm of Yellow he claimed his crew needed to bring down the spinnaker and he himself went to fetch the Yankee flag, a task normally performed by one of the crew. The finish line was fairly close to shore (about a 100 meters) and the flag was in front of the boat.
We discussed the incident in our Umpire debrief and had the following questions:

1. Should we have acknowledged Yellow's Yankee-flag and penalized Blue as keep clear boat? RRS 18.2(c)
2. Rules of Part 2 still applied, but one boat (Yellow) was no longer racing. Can you protest another boat in a Match Race when you are no longer racing?
3. Rule 22 states that: if reasonably possible, a boat not racing shall not interfere with a boat that is racing.... Should Yellow have kept up her spinnaker in full until after Blue had cleared the line, and thereby diminish the chance that Blue ran in to her transom?

In our discussion we did not come to a clear answer and tabled the matter for later.
Please give me your comments.