How could that be construed as illegal? For that matter you could eat them that night in a campground too. You could cook them in the duck blind for lunch, as long as you did not exceed a daily bag limit of birds, just keep remains of the carcass, ie wings, head, remains of feathers as proof. Going on what I was told, once cooked they did not count as possession.
And the link is the Federal Law, which may be different from the Missouri Code. Normally, a waterfowl violation draws both state and federal charges. But they only received a state ticket from MDC.
Daily bag limit. You can take only one daily bag limit in any one day. This limit determines the number of waterfowl you may legally have in your possession while in the field or while in route back to your car, hunting camp, home, or other destination. MOTEL?
Tagging. You cannot put or leave waterfowl at any place or in the custody of another person unless you tag the birds with your signature, address, number of birds identified by species, and the date you killed them. He could have labeled the birds and gave them to his son and vice versa, then they would have been legal according to the letter of this law while in transit from motel to home.
Dressing. You cannot completely field-dress waterfowl before taking them from the field. The head or one fully feathered wing must remain attached to the birds while you transport them to your home or to a facility that processes waterfowl. But they only have to be "tagged" after that with the above tagging information. Technically they took them to their home for the night, and processed them. People rent homes too, just like you rent motels. And once home, you can transport them without a wing or a head as long as they are properly labeled.
I am not trying to defend them or say the MDC was out of line. They were wrong and did not tag the birds with the proper label info like they normally do and they are not fighting the ticket. I always use the tags provided at the hunting areas when possible for waterfowl that you simply fill in the blanks for transporting processed birds. I have used a business card with my cons. id, date, and species written on the back. In the blind they are on my lanyard with my MDC id no.