He was not only 1 person, it is absolutelly sure. We can confirm that IT is not death for the same reason, "he"/"she" was lot of persons i think.
Just because you think that it's true doesn't mean that it's absolutely true. How do you know that it's 100% true? Have you met them before? Have you even seen anything that Satoshi said that suggests that he/she/they is/are a group?