Harry, I mostly agree with your assessment. I do question how likely it is that a starboard tacker carry themselves outside of the zone while doing their gybe - if they did that, they really screwed up the manuever.

If I were the port boat in this situation and the starboard boat is coming in tight to the mark - it's a no brainer. Slow down a little, let him in, and jump on top of him leaving the mark. There's no way somebody is going to gybe,drop,and round up without a wide ugly rounding.