Sure the guy shot was guilty of trespassing when he did not leave and instead he got belligerent back at the guy who threatened to shoot him. But the shot did not seem like self defense to me.
Relevant points of Texas law:
Sec. 9.41. PROTECTION OF ONE’S OWN PROPERTY. (a) A person in lawful possession of land or tangible, movable property is justified in using force against another when and to the degree the actor reasonably believes the force is immediately necessary to prevent or terminate the other’s trespass on the land or unlawful interference with the property.
Sec. 9.42. DEADLY FORCE TO PROTECT PROPERTY. A person is justified in using deadly force against another to protect land or tangible, movable property:
(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:
(3) he reasonably believes that:
(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.
Take a good, hard look at the build and size differences between the shooter and the overly aggressive meathead jock that got shot.
And that’s before I go into the actual self defense laws.