When Willie Afton jumpscares you, he practically kills you. He does no fancy stuff, like "stuffing inside an animatronic suit" (that is, if you're an adult an not a child). That's why you get a plain "Game Over" when you're jumpscared by him at FNaF 3, because, as a security guard, you're not inside an animatronic like the previous games, but you're simply "dead". As simple as that.
