Wow, all this about what's probalby the simplest rule to understand too.

Most, not all, sailors I've sailed with, or against have a great deal of integrity, and know for sure if they genuinely had to 'alter course', etc.
Usually if someone crosses ahead of you (cleanly), than it gives the crossed boat something to shoot for (pun not intended) on the next cross or mark rounding.

To me it's simple (LOL), if I'm S, and I had to alter course, I HAVE to hail protest if I expect them to do a circle.

If I'm P, and it looked TOO close and they altered some, etc., I do the cirle- part of the game.

It's about integrity of the self, the spirit.

There has been alot of great discussion here, by alot of very experienced skippers.

Carry on