Well, I'm very junior to the two judges quoted - but you know that doesn't keep me from expressing my opinion. I disagree with their analysis. The difference is how we apply the definition of "keep clear"

The key phrase is "with no need to take avoiding action". I think that in this case, P was keeping clear. Had S not replied to P's hail but simply held her course, then P would have kept clear by tacking. S did not NEED to take avoiding action. She CHOSE to alter course for tactical reasons. Therefore her action was not an AVOIDING action.

When S changed course, she was obligated under rule 16.1 "CHANGING COURSE" to give P room to keep clear. Because of the verbal exchange beforehand, any other action would have been a breach of rule 2 "FAIR SAILING".

My decision would be that no rules were broken.

Regards,
Eric