This is just my educated guess or speculation. I've read that Trump's SS loves him and I've read that he loves them. So, this makes me think they (or he) has selected Trumpists as his SS. That could introduce emotional handling of issues that arose or might not be totally competent at the job. Being politically loyal shouldn't be the priority for hiring for the security job but rather extremely professional, competent, cool, calm, collected, extremely physically fit, good vision, following procedures, willing to protect Trump's life and not cave to dumb decisions just because he says so, etc... BUT of course the way this narrative will play out among the QOP is Teh Deep State!!!11111!
Anyway, if there really were 3 snipers within the building, it makes sense, though it also might make more sense to be on the roof in addition to the base of the building...given the short distance (130 meters) to Trump. What doesn't make too much sense and is high risk is delegating to local, rural police a stop assassination type job. They have no expertise there in assassination prevention even if some of their training might overlap. What also doesn't make sense is the rifle and backpack story. Was his rifle in his backpack so he had to assemble it? If it was a long backpack with fully assembled rifle, he'd be stopped immediately, right? So was the rifle on the roof already waiting? None of the choices seem good there as in none demonstrate a good job by security.
Next, while the shooter was merely suspicious initially, there's good reason not to stop Trump from speaking. This is because there are probably many suspicious people at this kind of event. Many people they start looking at and watch.... However, the moment he disappears and the moment that the policeman confronts him and the counter sniper starts watching for him in that direction the threat level has become probable and Trump's security next to him should be triggered to do something.
To be open, I'm not that concerned about Trump. I feel like he's made his bed and can lie in it. I guess I am terrible to say so. I am far more concerned with the damage this has caused to others such as the people he tricks, the guy who saved his family at the event, how this plays out, revenge from the conservatives, and the exposure of SS security procedures and limitations to professional and international actors. The clown show has made us all less safe.