Can they even do that? In order to close-source it, wouldn't they have to remove the Linux kernel and basically rebuild the OS from scratch to keep from violating the GPL?
Some very good points here, all of which have caused me to rethink my original opinion. In fact, I've decided to change my opinion to the brain over the heart.
A line by my favorite actor in one of my favorite movies says it best.
"If your head comes away from your neck, it's over." -Sean Connery - Highlander
Teach them real orbital mechanics based on Newtonian physics, using Orbiter Space Flight Simulator, available for free at www.orbitersim.com
There is a large supporting community and many available addons, including several vessels from the sci-fi genre. You could teach them how ships really fly in space, as opposed to what they see on the movie screen