[Black Lives Matter people know that when a member of the public clearly has a gun and might be able to kill an officer, that member of the public might quickly be shot.
My former landlady had a friend whose boyfriend was shot dead by police in Virginia because he was coming down stairs at least a dozen feet away with a knife.]
“to see something”
Trump’s head - ~12 inches in size
sniper rifle - ~3 feet in length
Counter-snipers know what a rifle looks like.
https://www.reuters.com/world/middle-east/reuters-videographer-killed-southern-lebanon-2023-10-13/
The guy was with other press people in a known press area.