Absurd ruling.
So breaks anywhere else aren't of the same importance? What does it matter if a horse breaks on the line and actually loses ground. So what. No need to relegate them but they will be relegated in this instance.
A horse neck and neck will be relegated the exact same as a horse nose and rump.
Ok the rule is pretty clear but what happens if you gallop 100m out and get back into stride by the post. Adjudication of finishing position / gained advantage should not be any different just because you broke in a different part of the race.