Greg,
Very interesting indeed. If you have a transponder in your aircraft,
it needs to be ON. FAR91.215.c.(unless I am reading it wrong).. Much
different that not having a transponder, definitely NOT required in
that airspace.
Lucky that no one was killed. I feel sorry for the glider owner
that cared enough about safety to equip his sailplane with a
transponder yet it wasn't used during the flight.

Dean