Is this illegal or unsporting?

Can't see a problem in this case - you are playing the same game, using the same rules, in boats that aren't too different - not like a 70 footer v's a Sonata or something. Should you have carried on and sailed them off the course? I guess that would depend upon what the fleet had been doing up to that time - if the racing was pretty cut throat, then yes, why not? If the rules were just being used to know who had RoW for the rest of the series, then maybe a little out of place.

The Saljuice thing was a whole different ball game from what I remember.