The shooter was wearing cameo similar to what police might wear. They surely needed to be sure this wasn’t local law enforcement sniper before just blasting him.
Yeah the camo pants. They watched him for a while and both looked shocked when he fired. Was for sure a head shot. Sounded suppressed and only heard one shot like that
That is a plausible explanation, just hovering at threshold where it might seem believable.
But the counter-snipers are supposed to be briefed on the locations of all other counter-sniper teams. At best that explanation indicates gross incompetence of the security planners. That could true. And they could also have been working under extremely restrictive rules-of-engagement that required command authorization before firing.
Bang! Bang! Bang! Oops, too late.
There was no security team on that building used by the assassin. It was an obvious high-ground clear shot location and there should have been a security team standing on it.
I am still going with "the lack of coverage was intentional so that a volunteer assassin could get to a position of advantage". And also "this event was tacitly approved by factions within the government".
You are wrong. The shooter was wearing a pair of shorts and a T shirt with the logo of a popular Youtube firearms channel. Nothing about his clothes suggested that he was any kind of law enforcement officer.