Unfortunately, d33zy is not talking out of his ass -- depending on what State he's in. For example, the penal code of Texas allows the use of deadly force to protect property:

http://www.capitol.state.tx.us/statutes/pe/pe0000900.html#pe014.9.42

(1) if he would be justified in using force against the other under Section 9.41; and

(2) when and to the degree he reasonably believes the deadly force is immediately necessary:

(A) to prevent the other's imminent commission of arson, burglary, robbery, aggravated robbery, theft during the nighttime, or criminal mischief during the nighttime; or

(B) to prevent the other who is fleeing immediately after committing burglary, robbery, aggravated robbery, or theft during the nighttime from escaping with the property; and

(3) he reasonably believes that:

(A) the land or property cannot be protected or recovered by any other means; or

(B) the use of force other than deadly force to protect or recover the land or property would expose the actor or another to a substantial risk of death or serious bodily injury.

For the case in question, under Texas law, whatizame was (1) justified in using force (section 9.41 deals with when use of *any* force, deadly or not, is permissable for protecting property), and (2) when he reasonably believed the deadly force necessary (B) to prevent the other who is fleeing from escaping with the property; and (3) he reasonably believes that: (A) the property cannot be recovered by any other means.

Other states may have similar "make my day" laws (Oklahoma and Louisiana do), but Texas law isn't exactly the norm. In most states, you can only use deadly force if you believe you are in imminent danger of death or serious bodily harm. Otherwise, you are restricted to use of "reasonable force" -- no more than necessary to defend against the threatened harm. With the exception of Texas, et al, use of deadly force is never allowed to protect property.