As I expected, a wide variety of opinions!  I have already proposed adding the appropriate language to the SI.

The question remains:  Is a boat not racing but blocking the view of the starting mark "interfering" with boats attempting to start?

I like Tim's new "letter" score.  Since we now have NSC (Not Sailed Course) we might add NKO (Not Keep Out).

If I had been the race officer I hope I would have postponed.

Peter thank you for that as it’s a great example to put into our discussion. 

I agree with Charles, that how that rule is written is problematic because it goes against Introduction’s “…sense ordinarily understood ..”. (In contrast to the MR SI guidelines). 

I think it also has the problem that it seems to change 43.1(c), which is not allowed. If any contact is “serious damage”, then any contact is “damage”. It changes 43.1(c) by effectively striking 43.1(c) because contact now equals damage… therefore there isn't any contact that can satisfy the "does not cause damage" condition in 43.1(c).  No contact, no matter how slight, can be exonerated. 

That said, RRS 44.1 is not limited from change so the authors could get to where they are going more directly and leave defining “serious damage” out of it and completely rewrite 44.1.  But again, they would not be able to change 43.1(c). 

Further comments for the sake of completeness.. 

As pointed out above, the discussion is somewhat academic (although conceptually, still very important to properly understand how the rules work) if there is no valid protest. If the incident was observed by the race committee or protest committee (or even the technical committee), they could potentially lodge a protest so long as the validity requirements were met. In practice, this is more likely to happen if they believe there is a possibility that a boat has broken RRS 2. 

A boat knowingly touching a mark and not taking a penalty is the classic violation of the principles of sportsmanship. However, if the leeward boat was deemed by the protest committee to be exonerated under RRS 43 then it obviously follows they have not broken RRS 2 as they were not required to take a penalty or lodge a protest.

If the protest committee found that the leeward boat was not exonerated under RRS 43 then she would be disqualified for breaking RRS 31. It does not necessarily follow however that the boat has also broken RRS 2. If the leeward boat genuinely believed she could have been exonerated by the windward boat's actions, she has not breached RRS 2 even if her belief was mistaken. 

How do you establish whether the leeward boat had a genuine belief they were exonerated?  It's obviously not possible to get inside the skipper's head, so the protest committee would needs to find relevant facts in order to make an inference. For example, establishing what the separation between the boats was.  Other (more circumstantial) factors could possibly include the skipper's racing experience and knowledge of the rules. Notwithstanding the above comments, the fact the leeward boat didn't protest the windward boat could be a relevant factor, albeit not a conclusive fact. It's important to note that under RRS 2 a boat can only be penalised if it is 'clearly established' that the principles of sportsmanship have been violated, so the boat is entitled to the benefit of the doubt to some extent.

TLDR version - as always with any good question, the answer all depends on the facts! 

I like this requirement for two reasons: First, it makes it necessary for competitors to decide if they want to protest based on the incident, rather than as a matter of gamesmanship, based on the scoring for the regatta; and second, where I live, sailing is a 12 month per year exercise, and this cuts down on the number of times that I drive to the yacht club (30 minutes each way,) only to discover that no protests have been filed.

Back when this controversy was raging, I sent an email to Matt Hill asking if the liability insurance provided to US Sailing officials would cover this potential liability. I received an "I'll check" message from US Sailing (not from Matt,) but so far, have heard nothing. However, I did hear from a local judge who advised me that when she was deposed in a wrongful death suit about an investigation she participated in at the request if USSA, he/she had a real fight with the insurer about hls/her attorney fees for the deposition.