Don't fall for a logical fallacy, and try to view the situatiom from the lens of the information that they actually had, not the hindsight.
(from the transcript [0])
05:30 There's one guy moving down there but he's uh, he's wounded. ... 06:01 He's getting up. 06:02 Maybe he has a weapon down in his hand? 06:04 No, I haven't seen one yet. ... 06:33 Come on, buddy. 06:38 All you gotta do is pick up a weapon. ... 06:54 This is Two-Six roger. I'll pop flares [drop flares]. We also have one individual moving. We're looking for weapons. If we see a weapon, we're gonna engage. ... 07:18 Bushmaster; Crazyhorse. We have individuals going to the scene, looks like possibly uh picking up bodies and weapons. .... 07:36 Picking up the wounded? 07:38 Yeah, we're trying to get permission to engage. ... 07:59 Roger. We have a black SUV-uh Bongo truck [van] picking up the bodies. Request permission to engage.
There's nothing unclear here or anything to be misunderstood. If they had seen weapons they would have engaged already instead of asking for permission. It's just that the crew of the helicopter really wants to shoot them and that they, the US military nor the US public don't really give a shit if they are civilian as long as they can get away with it, which they can.
[0] https://collateralmurder.wikileaks.org/en/transcript.html
So to paraphrase "they did nothing wrong and even if they did it would have been okay".
First, they clearly shot civilians trying to take other civilians to the hospital by essentially inventing weapons they didn't and couldn't have seen. Secondly, in most countries when you get the responsibility to fly something like an attack helicopter, which takes a fairly long time to learn, you tend to have to be better than some random soldier. The "war is hell" excuse isn't really viable with the attitudes displayed in the video. But if you're trying to say that these are the kind of actions we should expect when the US invades a country then I guess we are in agreement.