Even in Texas I think firing through door at an unidentified target that hasn't presented any kind of threat should he enough to at least get him charged.
Can his lawyer make a case that he felt threatened is another story. If it makes you feel any better the last big court cases I can think of the juries were not bamboozled by lawyer tricks and got the correct verdicts ( Floyd, Rittenhouse, aubery)
We spent a whole class talking about is it ever alright to fire through your door last year and we concluded the answer to be almost never ever. Like can you see a weapon and they are trying to kick the door in right this second ? What kinda weapon? We concluded in almost all scenarios the answer is almost always no and it sure as shit shouldn't be the first move of the encounter. We concluded you better really feel threatened and be right and even then you still might end up on trial.
You really need to identify your target before you pull that trigger and be sure of the situation. It's going to matter for the rest of your life and not just to you but to a great many people.