I believe that it's not uncommon for the ejection seats in private L-39's to be inop, my guess would be due to the cost to keep them maintained and/or that the consequences of a poorly maintained system ejecting spontaneously or accidentally is worse than just having them disabled. I know that when I had the chance to fly the second seat in one, I had to wear a parachute and was instructed on how to pop the canopy and bail out in an emergency situation.