Let me clarify the question a bit, see if I can take out the ambiguity some:
Your name is Ted Tactician. You live in a state with a strong Castle Doctrine. Your home is built to withstand zombie attacks, except that, for some reason, you never got the front door very well fortified.
On this particular day, you are standing at the entrance to your bedroom, which you have designated the Safe Room in your house. Your wife is in the bedroom folding laundry. Your kids are in the room playing. Your "Safe Room" is essentially a bank vault that you sleep in. It has it's own filtered air supply, the door is literally a vault door and you've got food and communications equipment in there too. There is one window. It can be shielded from the inside by 2" thick steel shutters. As you are standing there talking to your wife, armed of course, you here two quick kicks on the front door. The door blasts open on the second kick. In jumps an intruder. He says "BOO! I'm here to rob you." and starts grabbing stuff. He's 50 feet away, because you have a big house. You KNOW without a doubt in your mind that you have time to get in your "safe room" and call the police.
Instead you draw your (insert favorite TEOTWAWKI weapon) and put two in his chest. He falls over dead.
Good Shoot or Bad Shoot?