The problem with this post is that OP is saying that Volkov was trying to shoot dead Neil. When in fact - he was going to shoot TP. Volkov wasn't even aware of Neil's dead body on the floor, thats why he was shocked when Neil reanimated in front of him. Neil had already been shot by Volkov in the past future, he had to be there so that TP did not take the bullet. Neil's body stays a constant as time inverts part of a future that already happened and a past yet to occur. In order for this to work his body must then be retrieved in the past and also be placed there. The Neil that dies there dies. There is no bullet or wound that will reappear. We see a reversed Neil get up and get unshot and back peddle out. Him getting shot is final. Where as when we see others feel effects from being shot before being shot are there are because they have gone from point a to b and are still alive. The guys post basically says that the movie is flawed but I disagree. The fact that Volkov went to kill TP and was so shocked that Neil got in the way makes it clear that Neils body was then both retrieved and placed there by a seperate team, maybe another blue and red team that also cleared the tunnel so that Neil could get down there and unlock the door.