There is alot of room for bias here. Is the fake foot a realistic proxy of an orgional? Can the snake recognize the difference? You don't fistfight a book or other object falling onto you. Would a snake bite a rock that shifted onto it when it bumps into it?

How much pressure is the fake foot applying? A person accidentally stepping on a snake would apply their whole weight because they didn't know it was there. Likely hurting the snake and warrenting a more significant and immediate response. I doubt the fake foot was applying the same force because of ethical reasons.

Edit: Phrasing