RE: Shut out in Missouri
I'm not going to speak on behalf of the MO DoC, but moving the season later in the spring is typically done for one reason: to allow sufficient time for the gobblers to have a chance to mate with hens. If the toms are hunted hard early on, there will be less mating and few poults come hatching time.
So yes, the state does want to keep the populations high, but mature turkeys as well as juveniles.
Sorry to hear of the big disappointment. Better luck next time!