I understand that. The Spot SOS was apparently treated as a Mayday as well - which makes sense (though I don't know what actual CG procedure is on Spot calls).
My point is that radio contact would have been established between the CG and the boat(s) if possible. From there a discussion would have occurred as to the nature of the emergency. I just wonder at what point in that discussion the Mayday became a Pan-Pan? No way to know of course - but it would be an interesting transcript.
Smack I can't speak to the US CG specifically. You are obviously more informed than I on the detail there. In my part of the world though, interestingly the rescue response that is triggered for a Mayday and a Pan Pan is almost identical. ( I am NOT suggesting anyone incorrectly call a Mayday for a situation that is a PAN PAN).
Like you said, it is also the nature of the CG and rescue services in general to jump to action, assume the worst case and go from there, it's actually part of the training, once someone rings a bell, any bell they go and make their own assessment.
Seems you want to have your cake on this and eat it too - Skippers take responsibility, but hold organisers of events responsible for ensuring skippers are responsible???
You end up with less rallies 'cause there a PITA to organise, high entry fees to cover your 'BFS approved' bumper sticker, skippers who are more concerned about meeting regs, than ACTUALLY being safe, and not much else will change.