The guy in black shirt with gun will probably be fine. He grabbed the gun, teal shirt guy felt threatened and got in his face. Black shirt guy stepped back and fired warning shot into ground. Teal shirt guy came back at black shirt guy, grabbed gun and shoved black shirt guy away. Teal shirt guy fired two shots. All on what I assume is teal shirt guy’s property. Texas crap.
Whether he's guilty or not likely depends on facts that have not been presented in this thread. No, the so-called "Castle Doctrine" does not mean you can shoot and kill anyone on your property. Black shirt was the instigator/aggressor because he went inside to grab his gun and then created a deadly situation. The warning shot, if anything, further proves he was the aggressor (I agree with MIR on this). In this instance, in order to use deadly force in self defense, you need to make a clear retreat and then be re-engaged by the other person. I don't see a clear retreat or intention to disengage. This jackass probably thought, mistakenly, that the "Castle Doctrine" allowed him to do that.
All that said, never gamble your life by insulting someone wielding a gun and, essentially, daring them to use it to kill you.