I am left with the unavoidable conclusion that supporters of SYG are simply looking for relief from questioning and/or prosecution after a self defense shooting wherein they had an opportunity to retreat but chose not to.
That is not the only conclusion one is left with and therefore clearly not "unavoidable" by any means.
Even if a person did NOT have an opportunity to retreat, they would still be forced to bear the burden of proof.
We all know, from your statements, that you would always choose the opportunity to retreat, but even you would be forced to prove that you didn't have that opportunity and would be convicted under duty to retreat if you failed.
SYG is not just about people who choose not to retreat.
Let's say a defender is forced to shoot in a situation where they reasonably believe that retreat is not an option. They considered the option and reasonably believed there wasn't one. Therefore, since they believe they didn't have the option, they clearly couldn't have made the decision to "choose not to retreat". They would still be forced to prove, in court, that retreat was not an option. If they failed, they would be convicted even though they did consider retreat and believed they could not take that option.
Obviously, I feel one should be legally obligated to consider retreat before shooting.
In that case, you would logically be against SYG. That's fine. The problem isn't with your opinion, it's that some of your statements exhibit some misunderstandings of precisely what SYG means. In addition, some of your arguments have logical flaws.
Because I believe if you kill a person when you had an opportunity to do otherwise, you've committed murder.
I believe the same as long as the "opportunity to do otherwise" is a reasonable opportunity.
For example: One always has the opportunity to not use deadly force by simply accepting whatever the attacker chooses to do. I don't consider that a reasonable opportunity to avoid using deadly force.
I do consider retreat to be an option but I also realize that it's not always a reasonable option.
I think if you're going to kill a man, for any reason, you should have to prove that you had no other "reasonable" choice.
Although I believe a person has a moral obligation to consider reasonable choices, I realize that the practical difficulty of proving that all "possible options" were unreasonable can make it impossible in some cases where the defender is innocent. As a result, I'm not willing to agree with the idea that one should have to prove that no other reasonable choice existed. Some things obviously need to be proved, but retreat is one that can be problematic.
In the case of retreat, I'm willing to accept that if a person violently attacks another person unprovoked and in a place where the defender has a right to be, the defender can use deadly force without having to prove that retreat was not an option.
Why?
Because this is all predicated on an unprovoked violent attack on an innocent defender. I don't think that it's fair to victimize the innocent defender a second time by forcing him/her to bear the onerous burden of proving that they couldn't have retreated.
You talked about being innocent until proven guilty as if it were a good thing but there seems to be a disconnect as it applies to SYG. What you're arguing for is starting any self-defense case, by assuming that the defender is doubly guilty. This is because the defender must first admit guilt in order to claim self-defense and that imposes one burden of proof. The duty to retreat imposes a second burden of proof.
So the defender, in order to avoid conviction must prove first, that they couldn't have reasonably retreated in order to claim self-defense. Then, once that is out of the way, they must also prove that the other circumstances of the case were consistent with a claim of self-defense.
I believe that retreat, if and when possible, is a reasonable choice.
Retreat is a reasonable choice when it is a reasonable choice. The fact that it's possible doesn't automatically mean it's reasonable.