apparently not. I looked it up out of curiosity:

the requirements for lethal force:

• Person not engaged in unlawful activity;
• Person in a place they have a legal right to be;
• Reasonable belief of imminent danger of death or serious bodily injury;
• The danger creating the belief of imminent death or serious bodily injury is real, or honestly believed to be real at the time;
• The belief is founded on reasonable grounds.

this would fail the last one.

He can shoot at people because he was sold a gun and anyone who has a gun can shoot at anybody they decide. What we’re actually waiting to learn is “Will this former responsible gun owner get away with shooting at people?”.

If the answer is “yes” then other gun owners are going to do the same thing because they want to shoot at people.

If the answer is “no because he didn’t have a ‘no trespassing’ sign” then gun owners are going to buy “no trespassing” signs and then shoot at people, because they want to shoot at people.

I don’t think a good-faith misdelivery is trespassing, so no. Unless you want any delivery to be done by throwing the box from the curb.