Didn’t he travel a good distance to “defend” a business, one he had no right or reason to defend with a deadly weapon?
Yes, which is not murder or a component of murder.
Was it really just that Washington is a “stand your ground” and not a “duty to retreat” state that made him innocent on that?
No, and I think this is where a lot of the hysreria around the trial came from. He didn't stand his ground, he ran away was being chased. One of the men chasing him was trying to grab his gun, and another pointed a gun at him.
I think the great majority of the people calling him a murderer have never actually looked into what happened that night.