This manoeuvre did not involve waiting for the stall, followed by what may be considered normal intentional spin entry procedures.
This was a rapid application of left aileron until beyond 90deg followed by a hard pull as the rotation continued,
If the maneuver did not involve waiting for a stall, it was not a spin entry (to be proud of, anyway). If it involved a steep roll and a pull it has the signs of a spiral dive, or some kind of wingover.
It is very important for pilots to recognize and correctly react to one vs the other, in recovery. The recovery for one, applied to the other situation, could be messy. I accept that the other pilot flying the glider flew a purposeful evasive maneuver (which worked), but as I understand the description, if that pilot was asked if they had deliberately spun the glider, I doubt that answer would have been yes.