The sample doors are just a flap that gets blown open by the nitrogen during sample gathering then springs shut, there's no direct control over them, the solution is to just pack it away in the return canister very carefully.
I figured it couldn't be that easy or they would already have considered it. Springs are probably more reliable for that application on a spacecraft. Thanks for clarifying that for me.
My rule of thumb is NASA/JPL/JAXA/ESA are full of far smarter people than me so if I think of it in 5 minutes they definitely thought of it already and have a binder full of reasons it's not the best option.
