I don't think it made it more difficult for a starboard gybe boat to force it's way in at a c-mark rounding. I don't think it changed much. If you read 18.2 e) again and focus on the details, I think you can pretty much forget about trying to apply it.
(e) If a boat obtained an inside overlap from clear astern and,
from the time the overlap began, the outside boat has been
unable to give mark-room, she is not required to give it.
Even if you could argue that a starboard gybe boat obtained overlap from clear astern, you're going to have a hard time arguing that the port gybe boat is "unable to give mark-room from the time the overlap began" since opposite gybe boats are overlapped pretty much from the moment they become opposite gybe boats.
I still would like to know what circumstance would prevent the port gybe, outside, boat from being unable to give mark room. This rule applies like a domino to any of the more outer pinwheel boats so you can't argue that starboard gybe boat was not entitled to room because the port gybe boat had boats stacked up outside her.
