Hey Eric,
With the benefit of video (and pause), I see some potential flaws with your facts found at Time 4. To me, it looks like when SD/red gybed, she was not in the zone (defined as when the HULL reaches the zone of three HULL lengths). When I looked at the video and paused it, it looked to me (especially at 0:07 when zoomed out to see the mark), the gybe occured outside the zone (looking at the wakes), and PD/black was never overlapped inside of SP/red prior to the collision (and SD/red entering the zone). These boats have long poles, so it makes them look longer than they actually are.
Having said that, I don't know how easy it would be to get to that conclusing in a real hearing, without the video. Witness testimony may or may not have helped with the speeds involved.
I don't agree with PD/black breaking RRS 10, at all. PD/black was coming in hot on the layline (probably overstood), and SD/red gybed to round the mark (proper course). Had she continued on STBD and forced PD/black to gybe, that would be a different question, and may have caused a RRS 17 issue, and almost certainly would have brought SU2 into the discussion.
Said another way, I think that in the absence of PD/black, SD/red would have gybed there anyway (or perhaps sooner).
The only thing that PD/black did wrong was to then come into the zone and round inside of SD/red without rights (I maintain that PD/black did not have inside overlap when S/D red's hull hit the zone); although the room may have been freely given, since SD/red was probably dealing with the trauma of the collision.
I think that SD/red gets DSQ for RRS 11, and it probably stops there.
Mike