How Low to Spin??

Interesting problem. I would suggest that the primary danger faced by
a competent pilot isn't a spin, but a midair collision. One can choose
to increase speed near the ground. However, a low save requires extra
attention to airspeed control, coordination, and thermal centering.
Myopic focus on a thermal in the high density traffic of a landing
pattern is inappropriate. Pilots entering the pattern depend on others
already in it to act predictably. And once in the pattern, special
attention has to be given to traffic aviodance, since gliderports (and
especially mixed traffic airports) can produce unusual conflicts under
the best of conditions.

I assume your club has a safety officer. If a pilot chooses to thermal
in the pattern, that pilot needs talking too. Part of the discussion
might include the addition of variables during low altitude saves and
their effect on maintaining appropriate safety margins, but the
primary focus should be on the poor judgement that led a pilot to
operate unpredictably (and thereby unsafely) in the landing pattern,
where he may be a danger to others as well as himself.