The details get a little tricky, but the best case for the defendant seems to be under Title 2, Chapter 9, Subchapter C, Section 9.31. Specificaly whether (1)(A) applies and the decedent:
unlawfully and with force entered, or was attempting to enter unlawfully and with force, the actor's occupied habitation, vehicle, or place of business or employment;
Looking up "habitation" it seems to apply to the porch in that it structurally part of the house per Title 7 Chapter 30 Sec 30.01 (1) (B).
As far as the decedent entering the porch unlawfully, I think that is obvious as he was told to leave by the land owner.
Which leaves one crucial question, was the entry "with force". Now I have not yet looked this up do to needing to end my lunch break, but it does not seem in the ordinary layman sense of the word to me he used force to enter the porch.
So I am still not entirely sure the self defense works.
Simple assault qualifies as force. Those chest bumps qualify as simple assault, and at the end of the video, he was forcing the homeowner back with them.
Game over, he loses. But the key in this incident is the fact that no charges were filed. The 9.3* series tends to be couched as “it is a defense to prosecution” whereas 9.4* declares things flat out legal, barring charges from being filed. Self defense incidents often results in charges laid before the grand jury, for the grand jury to decide if self defense applies. Property defense incidents where actions are clear result in the DA not filing charges as the declarations of legality in 9.4* mean they can’t.
The homeowner is covered by both, but the lack of charges at all probably means that the DA agrees that this is covered by o.QRS and 9.42.
9.31 (2)did not provoke the person against whom the force was used; and
This was an additional requirement to use (1) that would be met if we considered the entry to the porch and subsequent belly bumping to be "with force".
It seems hard sell to me to argue that the defendant did not provoke the decedent when he decided that to end an argument he was going to threaten to use deadly force.
I find this restores some faith in the reasonableness of the self defense law. It seemed ridiculous to me that one can bait a person into being enraged and then shoot them dead because they were bumped on their porch after provoking the reaction...and claiming they were just defending their home.
I am all for shooting real home invaders that smash their way in to steal rob or destroy. Just not so fond of people abusing such a law as a trap to murder a rival in a bitter dispute.