A threat’s a threat, I doubt snakes are aware of the fact that they even have venom, much less that it only works on certain living biological entities. But I’m no Snake Scientist, so I could obviously be totally wrong.

They aren’t worried about what sort of appendage is going towards them. They don’t have that level of cognition. I should think that if you piss off a gorilla with a fake leg, that gorilla would understand that it’s a fake leg and still be mad at you.