Missing from 200 meters with an AR-15 is... Anyone with more than a day's worth of target practice, with a target that big, is either ridiculously unskilled or wasn't shooting at that target.
Are you speaking from experience with that weapon at that distance? My experience with anything bigger than a .22 was one evening with some friends who were sighting in their hunting rifles. Only one of the five was able to hit a target that size at that distance with any reliability.
I would estimate with training should be able to hit the target half the time. But there were probably factors like his glasses, not military grade eyeware, just Trump's upper portion in view, bad angle of his position to avoid counter sniper, small window of time, etc...who knows really.
Yes, I’d say there are more than enough unknowns to refute a claim that someone who missed him must have been aiming elsewhere.
On a day without rain in my aperture, with ironsights, at a range of 200 meters, I could hit a popup target as well exposed from that angle at better than 85% of the time after a three days of shooting practice, 90+ if prone.
With a well dialed scope, practicing shooting every day, I could hit that target 99+% at that distance without windage flags with a M16, especially if the scope had a range finder that I could practice with. 500 meters is where it would get really iffy.
I have had standard military marksmanship training. The last time I had an AR-15 style rifle (an actual m16-a2) in my hands was in 2010, and the last time I handled a weapon was in 2013 or 2014? I went shooting at a range with my hillbilly friend (he identifies as such; he's literally from the Carolina countryside, from a family of moonshiners), but that was handguns and a rifle, not ironsights.
The shooter had a ammosexual YouTube channel, shot every day, and counted himself a gun afficionado.
Assuming the gun nut knew to teach himself how to shoot and where to shoot, he should not have missed. That was a pretty close shot for that rifle, unless he was using ironsights, which I doubt.