You CANNOT shoot someone simply for being on your property in KY. You cannot use lethal force to protect your property in KY. You MAY use lethal force if they are in your house, trying to get into your house, or trying to burn your house or another building down on your property.
He's correct and it's a basic principle, you can ONLY use lethal force IF lethal force is threatened and you have reasonable belief that you're life is truly in danger. (eg. Someone charges you with a knife at close range, someone runs at you swinging a baseball bat and screaming they're going to kill you).
Disparity of Force is a LARGE part of justified use of lethal force in reference to an unarmed attacker! There's also a matter of "AOJ"
AOJ means "Ability, Opportunity, Jeopardy":
Ability means that the other person has the power to kill or to cripple you.
Opportunity means that the circumstances are such that the other person would be able to use his ability against you.
Jeopardy means that the other person's actions or words provide you with a reasonably-perceived belief that he intends to kill you or cripple you.
If all 3 of these are met then defense with lethal force is legal!
This site will explain it in more detail from the man himself:
http://www.corneredcat.com/Legal/AOJ.aspx
DISCLAIMER: I AM NOT AN ATTORNEY, ALL INFORMATION CONTAINED HERE IS FROM PERSONAL STUDY & RESEARCH. "AOJ" IS A MATTER OF LAW THOUGH, A MEASURE BY WHICH ALL SHOOTINGS ARE JUDGED!
Here's an example of Disparity of Force in reality:
http://www.startribune.com/local/south/25472764.html