In ethics, the question would be answered by "yes, this ethical system is the only acceptable way to make decisions" by definition. In practice, this fact is not sufficient to make more than 0.01% of the world anywhere near heroically responsible (~= considering ethics the only emotionally/morally/role-followingly acceptable way of making decisions), so apparently the question is not decided by ethics.

Instead, roles and emotions play a large part in determining what is acceptable. In western society, the role of someone who is responsible for everything and not in the corresponding position of power is "the hero". Yudkowsky (and HPJEV) might have chosen to be heroically responsible because he knows it is the consistent/rational conclusion of human morality and he likes being consistent/rational very much, or because he likes being a hero, or more likely a combination of both. The decision is made due to the role he wants to lead, not due to the ethics itself.