Someone who is not capable of understanding cannot be expected to follow it, like the mentally impaired. You cannot expect them to follow the golden rule perfectly because they lack the mental capacity.
ALL animals eat plants, and so those "deaths" are unavoidable. Herbivores eat plants directly, while carnivores eat plants indirectly, by eating the herbivores that ate the plants. All animal nutrition ultimately comes from the plant kingdom. According to electrical impulse stress tests done on plants, they like being eaten, even though they don't like being damaged for its own sake, for example they don't like being burned. There was a book I read about it called The Secret Life Of Plants, by Peter Thompkins and Christopher Bird.
Plants don't have nervous systems, and because they are rooted to the ground, they have no sovereignty. Basically though, because animals are poor converters of plant protein into animal protein, when you eat animals, you actually are causing the deaths of MORE plants than if you ate the plants directly. So it is either cause the death of plants by eating them, or cause the death of even MORE plants, AND the animals by eating the animals. It is no contest. The vegetarian diet causes far less death and destruction in the world than does eating animals.
Deserving it and asking for it do not mean the EXACT same thing. They have slightly different connotations or implications. Deserving it implies that someone actually deserves to die, whereas asking for it means that someone does something, whether intentionally or unintentionally, that naturally provokes another to kill them, which causes their death, even though they may not actually DESERVE to die. DESERVING to die implies that someone is a danger to others in general, and should die, or be sought out and assassinated whether they happen to be doing a threatening act at that particular time or not, because knowing their character, it is only a matter of time before they WILL do something to threaten another. Someone might deserve to die without even threatening another, and deserve to die only because one is absolutely certain that they WILL do something in the future to hurt others. Alternatively, someone could attack a police officer because they want the police officer to kill them, because they lack the will to kill themselves. These people need help. Do they really DESERVE to die? Not necessarily. They are just ASKING to die. Asking for something and deserving something are NOT the exact same thing, whether it be being killed, getting a raise, or being hurt or helped in any other way.