Just for the purposes of discussion -- I would NEVER NEVER do this, of course! -- who says that an airline needs to be told about a death? If you know the deceased's PIN, you can continue to order awards from the account until it's cleaned out. Airlines don't match their frequent flyer account records against state-issued death certificates, like Social Security does.
In this case, that deception is unnecessary because Delta is pretty obliging about transferring miles, but wouldn't my approach work in general? Only if you know the PIN, of course.
Bruce