Well you said that way better than I ever could! lolAgreed.
The AR-556 Crooks used was a good gun for a 140 yard shot, IMO.
But the SS Snipers looked like they were using AI accuracy international bolt actions in 308 or 300 win mag with Nightforce 5-25x or 7-35x scopes. Deadly 1000 yards+
Secret Service Counter Snipers have very stringent qualifications on skills and physical ability, including eyesight and hearing: Special Operations Division: Counter Sniper Team (CS)
I just know that any elite group that would have snipers are going to be the best of the best. They look the part and act the part. I didn't know all the specifics like you do, but I know enough that 20 year old Tom C was not it and any sniper peeking at him from afar was going to realize that very quickly too. Now the average person in the crowd maybe though he could be part of something official (but based on the people yelling for LE to get this guy who was up on the roof, I'd say they weren't fooled either), but no way any of the LE there looked at him and decided he was part of a sniper team from any of the agencies helping with security.