Invalid argument: The "potential person"

Someone told me that a fetus is not a person because it can't think, feel and be self-aware. It's merely a potential person until it possesses those qualities. Therefore it is not immoral to end it's life.

By that logic, if the same person tripped over his ego and knocked himself temporarily unconscious, he too would be unable to think, feel and be self-aware. Now he could potentially wake up again and regain his personhood, but until he does he's only a potential person, and therefore it is not immoral to kill him.