they don't realize that whether the snake constricts them or they die from CO2, they are still getting suffocated to death. as CO2 competes for space in the lungs, it keeps oxygen from properly transferring. same kind of feeling as holding your breath for too long. same kind of feeling as suffocating to death. they could argue that the snake squeezing it hurts the rat more. you could ask them if they've ever felt the burn from inhaling CO2. I've seen snakes kill rats quicker than CO2 chambers and vice versa. either way, the rats gotta die and your snakes gotta eat. its the circle of life.