Other stunts say you can only use them against humanoid opponent, but not Disarm?
Can you knock it’s teeth out?
I ask as I watching Dave rule that you can on VCGs stream...

Disarm is to "knock or pull a weapon or other object from your opponent". So if anyone holds a weapon or an item, you can use the stunt to make them drop it. Someone that doesn't have a weapon is unarmed and cannot be disarmed.

Disarm the giant bioweapon killing machine?

Shouldn't be possible as every inch of it is designed to kill.

Plus it kinda defeats the purpose...

I agree

Disarm the giant bioweapon killing machine?

Shouldn't be possible as every inch of it is designed to kill.

Or maybe it is!
GM: The Alien rears up, hissing with malice and jaws drooling slime. It's the perfect killing machine and it's about to demonstrate it on you. What do you do?
PC: I disarm it.
GM: Wait, what?
PC: I got 7 successes.
GM: You can't do that! The entire creature is a lethal weapon!
PC: I know. That's why I disarm it.
GM: Disarm it from what?
PC: I don't know. The story?
GM: ...
PC: ...
GM: *Sigh* Ok, you disarm the Xenomorph from the story and it disappears entirely.
All the PC-players *yay*

You disarm the alien by killing it

@Enigma - LOL

You disarm the alien by killing it

... and you can even disleg it 

or dismouth it

or dismouth it

I feel you should start with that.

or dismouth it

That’s actually what happened when co-host Dave ran a game for VCG.