That Slate article doesn't say what you think it says. A pre-emptive pardon can only be issued for someone in danger of being convicted of a crime; it is essen

That Slate article doesn't say what you think it says. A pre-emptive pardon can only be issued for someone in danger of being convicted of a crime; it is essentially a grant of immunity. A dead defendant who was merely charged with a crime can never be convicted of the crime, so a dead defendant cannot be pre-emptively pardoned.