It doesn't mean people cannot criticize the Disneyfication of plot elements. Baron Zemo shows what can be done when not catering to blatent black and white lines of good and evil.
I expanded on my point in my edit. You are trying to use real world logic and reasoning to excuse the murder of an unarmed man in a universe where heroes are real and things don't make sense. And even THEN you would still be wrong because what Walker did was wrong no matter how many ways you try to slice it.
- Walker made the wrong tactical decision because he could have captured him. He could have provided them valuable intel on how the Flagsmashers work. Their Hierarchy. Their network.
- Walker made the wrong PR decision because he murdered an unarmed man in broad daylight on foreign soil in front of a crowd of people.
- Walker made the wrong moral decision because the man was on the ground, unarmed, had his hands up, and was borderline begging for Walker to not do it. He literally screamed "IT WASN'T ME" before Walker beat him to death with the symbol of America.
I have no idea why you and others desperately want Walker to be the good guy or to have done nothing wrong, but by every objective measure what he did in that square was wrong. If you don't like that he was put in that position by the writers or you just don't like the writing in general then that is one thing I will completely understand that viewpoint, but don't give me this "he did nothing wrong" nonsense because it is just stupid. He was clearly wrong even by our real world standards. You don't just brutally beat unarmed people to death once you have them cornered and subdued. That is some inhumane bullshit that is far below the standards of an American soldier let alone "Captain America".