Gas them through closed doors

So I was assaulting a downed medium aircraft yesterday. A Ceasan was directly behind the spaceship door, occasionally poking his head out and taking pot-shots at my troops. On my turn, the door was closed and I had an epiphany...shoot the closed door with a stun rocket and see what happens. Sure enough, the stun gas rocket exploded against the closed door, the alien got the full blast of the gas, and down the alien scum went...all behind a closed, solid, air tight, alien alloy, metal door. Is this working as planned or should the stun gas have stayed outside the door and not affected the alien at all?

The aliens normally use only the screen doors when landed because they like fresh Earth air.

The rocket has an AP head that breaches the door and then releases the gas. It's science.

You can also close doors a split second right after a solder tosses a grenade. Negates return fire. Especially handy for when you've decided to just saturate the craft with C4 and damn the collectibles.

Maybe the gas seal was broken when you shot the craft down.