So, if you are wrong and it is possible to draw from a sitting position, would the fact that the shooter was seated when attacked change the situation? Was there a reasonable expectation on the shooter's part that he would not be attacked?
No you do not have to stand to draw a pocket piston/subcompact pistol from a pocket. I carry a subcompact in my back pocket all the time. All I have to do is lean slightly forward to allow it to be quickly and easily deployed. I have not read anywhere if he was standing or not but the assumption that he had to be standing is completely wrong.
The witnesses said he drew his firearm and fired. There is no report that he brandished his handgun as a threat. This actually supports his contention that he believed he was in danger. When the guy who got shot stood up and turned on him, yelling and threw something in his face he reacted. There was not time for a thought process. He reacted as he was trained to react.
The courts will sort all of this out. There are still many things that have not been reported and we do not know. What I do know is that they both made very bad decisions and this was needless and never should have happened.