Honestly, I don't like this... Pressing X in the inventory only clears this particular soldier, so why would it be different with craft?
As a player, in 25 years of playing X-com, I've often needed to remove all soldiers from a craft, but not a single time I needed to unload all the craft. And I already know that X is associated with clearing the current item... This doesn't add up at all.
I really think X and Z should be swapped here. Please.