So some of you bring up some good points.
1. He was seen leaving a construction area- unless it was posted I don't think this is a crime. As dawg80 said, I also love to visit new construction and see houses going up and how they are laid out. Nothing wrong with that.
2. He was suspected of being a burglar who had stolen things from houses recently. I will give them the benefit of the doubt and say they suspected him because they saw him running from the construction site. This would give them probable cause to report him and possibly even try to keep an eye on him.
3. In the video a few people have pointed out that he initiates the contact. I don't really want to watch the video again, but in my memory we see him run along the right side of the truck with redneck #1 by the driver side door. Then the video loses them for a few seconds ( I may be wrong on this) and we see the two on the driver side of the truck struggling with each other. I think that supports the theory that Ahmaud made the initial contact. I don't know what happened in the spot the camera cut away ( or that i am just blanking on) but we can't know if there was something that caused him to try to get the gun away from the guy. We only get one side of the story.
4. HogDawg mentioned that initiating contact and trying to wrestle the gun away was a stupid thing to do. This is true if you want the people who are about to kill you to get convicted of murder. Fighting for the gun definitely is a dumb thing to do. If you are actually trying not to die it is not a bad option. It didn't work out in this case, but if someone is going to shoot you, trying to get the gun away from them is a valid option.
5. A couple people have brought up murder charges. This is a great point. Murder is a tough sell and likely a path to them walking away free and clear. If they pursue murder and don't get the conviction people will be outraged. If they pursue a lesser charge like manslaughter people will be outraged regardless. I still think pursuing a lesser charge is the proper course of action.
In my opinion something has to be done.
Little hypothetical real quick.
You (directed at anybody) and I live in the same neighborhood. One day I see you out for a walk and decided to stop you on the street and confront you about stealing my petunias. You have no idea what I'm talking about and deny like the lying Trump supporter( or crazy liberal) you are. You're getting a little angry and I know you are a crazy (insert political affiliation) so you're probably armed. I decide to pull out my handgun (I have a CCL) to be ready for you. As soon as you see the gun you think "this nutjob is about to shoot me over some petunias" and decide to try to get the gun away from me. I fight you for the gun and have to shoot you to stop you. Who is acting in self defense in this situation? We both have a right to be in the street. My gun is legal and legally carried. You initiated the physical contact.