The A/C type is irrelevant - if we'd bought them [K13s] they'd be grounded too for the same reasons
Probably, and it could be even worse - quite a few are being grounded permanently with glue problems. Also they may not be suitable for a big porky P2 and a big porky P1 and they might have made the same sort of demands that meant they didn't get K21s.
https://en.wikipedia.org/wiki/Schleicher_ASK_13
Empty weight: 295 kg (650 lb)
Max takeoff weight: 480 kg (1,058 lb)