Well, I haven't even read this analogy and I know that's wrong. There are heterosexual men who request to be pegged by their female partners. Indeed, I'd wager that the vast majority of emergency room presentations for foreign objects in anuses are adult heterosexual men who put the objects in themselves.
Your analogy is ambiguous. Did the top ignore instructions? Did the top get carried away? Or did the top do everything that was agreed to and only that? It seems to me when you agree to receptive anal intercourse you are or should be aware that it can hurt or damage you. If you go ahead and consent, in what universe have you not accepted that risk? In what universe is one party to blame but not the other who equally participated in the action causing the tear?Anal tearing is a risk with anal sex. The risk is increased if the anal sex is rough, or if there isn't sufficient lubrication. Obviously, not all anal sex will result in tearing. And also obviously, it takes two to engage in anal sex, so it's consensual.
Is it the responsibility of the bottom to ensure that the top doesn't get rough? Is it the responsibility of the bottom to ensure that the top uses sufficient lube and adds more as needed to stay safe?
Even if the bottom takes all the right steps - tells their partner to use lots of lube, insists on him not being rough, etc. - if tearing occurs, that harm is born entirely by the bottom, isn't it? If the bottom takes all the responsible steps he can, and still ends up torn, who is responsible for that tear?