The jury has no reason to contemplate a dead person's right to self-defense, it is irrelevant, they are not on trial. As I've repeatedly said, multiple self-defense claims can exist without being contradictory. It wouldn't matter in the least if the victim had no harmful intent and was attacking in clear self-defense. Though admittedly a jury might swing on that, and the defendant if we still had hangings. What matters is if the defendant believed their life was in peril and if that was reasonable. Again, two guys here cries for help, here a dangerous madman with a gun has run into that abandoned warehouse, both run in, both turn a corner, both see a man with a gun, both had self-defense rights and neither was acting with any criminal intent, at the survivors trial all that matters is his right to self-defense. You seem to almost consciously avoid this line of reasoning.
If the jury has no reason to contemplate the victim's right to self-defense, then there is no purpose to a trial. Everyone who claims self-defense can just go home, nothing to see here. The reason I say this is because establishing why the victim got into the situation where the defendant felt they needed to kill is a key to setting up the motive of the killer. If the killer makes the first physical contact, they are supposed to be declared the aggressor and therefore have no right to a self-defense justification. Therefore, by not deciding if the victim has a right to self-defense in such a situation, we are using the killer's narrative as the basis for deciding if the killer is guilty or not. As we keep coming back to it, killers will lie if they think they can get away with it. Therefore the killer's testimony should be analyzed to make sure that the victim was justifiably defending themselves against the killer, and did not just coincidentally happen to do something so terrible that the killer had justification for self-defense claims.
Example: If I follow you and, without identifying myself or my intentions, try to chase you down simply for walking home from the store, am I acting aggressively?
The answer is: It depends, depends on a lot of things, and since it does, the answer can be no or yes. It will depend on the individual being approached, the approaching person's manner, where and when we are, and many other factors. One big one, I wouldn't assume someone was chasing me down simply for walking home from a store unless they had been tailing me since I left the store.
Continuing the hypothetical: If someone follows you for several blocks in their car while you are walking back to someone else's house which is not your own (friend, relative, etc -- this is because you are, for whatever reason, not in your normal neighbourhood), and they do not identify themselves but instead keep slowly following you in their car. At a certain point, they get out of their car and begin walking your direction, quickly trying to close the gap between the two of you. When they reach you, their first question is "What are you doing around here?" Now, is this hypothetical person behaving aggressively? If the answer is yes, then the definition of "aggressor" needs to be changed as I said before. If the answer is no, I'd like to know why.