I think your assessment sounds consistent with what I’ve been following in this trial.In my opinion it wasn't the smartest decision to go there in the first place but he had a legal right to be there and a legal right to have the weapon he had (doesn't matter if it is an AR or a .22 handgun). What firearm he had is irrelevant in this case. From the video I saw it looks like he was hit in the head with that skateboard? Or at least the other guy was aiming for the head? That could be construed as deadly force. The legal definition for deadly force is 'could cause death or serious bodily injury'. Being hit in the head by a swinging skateboard while on the ground could very well be seen as deadly force. If he was able to articulate that to the jury then that shoot could be considered justified. I don't know the sequence of events so can't say about the other shootings but it all comes down to how well he can articulate that he felt he was in danger of death or serious bodily injury.
DISCAIMER: I am not an attorney but have a few years of law enforcement experience and several college level courses in criminal justice (I started out as a criminal justice major)
Thanks for your disclaimer and transparency. Another guy(?) on here @El Capitan ran data cables at a hospital but went out of his way to portray himself as a doctor, cardiac specialist and of course, immunologist. Likely Napoleon complex….