Bad SOP, imo. They appear to be acting as if they are in downtown Fallujah instead of a college campus. One accidental loud noise and you could easily have one of these officers inadvertently squeeze the trigger causing unintended harm. Also, having everyone up close like this puts them in an immediate close quarters combat situation if the guy was actually a bad actor. A little distance gives a better perspective and time to make better decisions.
Finally it sets up an immediate confrontation if the guy is unarmed but simply reacts poorly to being stopped. What if he says "Its an umbrella, you dumbhead, eff off!" The guy with the rifle aimed at the back of his head may only hear the last part and react to that with potentially catastrophic results.
This is the result of equipping everyone with heavy artillery and SWAT capabilities. When you have it, you want to use it and will do so at the least provocation. If all they had was their side arms they might have investigated from a distance, identified the umbrella and called all clear. Had the initial scouting determined they did have an active shooter, they could have isolated him and still had time to get a SWAT response from say the county or higher level municipality.