Just for discussion, I'm mostly neutral:
50 milers, and up, are timed in at the finish line. The horse has one hour
to meet criteria. I've never heard of anyone being disqualified for
recovery after the 12 hours time allowed. Has this happened? I know of
several times when riders just barely made the time at the finish. There
was no question they had "finished" even though the horse was not yet
checked and judged "recovered" and "completed" for a while, within the hour
of course.
In the case of LDs the rule seems to be ambiguous, and I've heard of it
being used both ways. "Must recover before the time cutoff", or "they
crossed the line and still had 30 min to recover", even if recovery was
outside the 6 hours allowed. (Placings, if given, in the order of
recovery.)
My take is all distances ought to be handled as nearly the same as possible.
I do think LDs should be able to recover in 30 min at the end just as 50s
and up must do during the ride at similar mileage points.
In any case this rule needs to be clearcut.
