1) Why would Locke try to squeeze under an inch-thick steel door being held open by a simple toolbox when he could just climb through the pantry's air shaft as he instructs Henry to do afterwards?

2) What good are inch-thick metal blast doors when any explosion "outside" the living quarters would simply be forced through said air vents, and out through the pantry, incinerating anyone in the living quarters, anyway?

I could buy the air vent in the armory, since it also has an apparent steel door covering it, but the pantry is just a regular door as far as I know. It's not obviously intended to contain an explosion...