And, you have to identify the issues and stay laser-focused on the issues.
Issue #1 is if Junior and Senior and Dash-cam Man were even allowed to chase Arbery and attempt a citizen's arrest. My understanding is that they would have had to witness a felony in order to do so, and the evidence so far indicates Arbery only committed a misdemeanor. I believe that is the basis for the "Criminal Attempt to Commit False Imprisonment."
Issue #2 would be the self-defense argument. I don't think it applies as stated above. Junior shot and killed Arbery. He wasn't allowed to chase him, and he isn't allowed to claim self-defense. He is likely getting convicted.
From what I've read so far, I don't think dumb and dumber were allowed to pursue the guy either and in that case, it's going to be hard to prove self defense.