But does the contract under which Satan holds his soul actually have terms preventing cops from learning to do the same, or is it possible your friend just can't recite the plot of every episode of Game of Thrones and every HS/college/pro football game played during the times he "ain't got time to practice?"
And, unless there was reason to believe the guy had duct taped pregnant nuns to every inch of the room except where he was shooting out of, then the safe target area isn't human torso sized, it's roughly 8' high and (guessing by the room map) 50+ feet wide. Yes, you need better than that to kill him, but just keeping him distracted would save lives. Even Whitman resorted to shooting through the scuppers once there was meaningful return fire. No telling how many people didn't get shot because they weren't on the limited field of fire that offered him. The Vegas shooter wouldn't have had any real cover to get behind.
I'm going to assume that you may be serious, that you just might -- possibly -- not be trolling, so I'll dignify this with a response.
He's out in some farmer's field, shooting at ground hogs. There are no occupied hotel rooms above, below, or to either side of his line of fire. The distance is known, it's daylight, his scope is zeroed for 500 yards, and he's not taking incoming fire so his adrenaline isn't sky high. And, of course, he's shooting a rifle that was built and set up specifically for long-range, precision shooting -- not an AR-15 patrol carbine with a 1x holographic sight. There is a difference.
The Texas Tower sniper is not an appropriate comparison. Yes, civilians with rifles eventually pinned him down. But he was up on the tower by himself, he wasn't surrounded by occupied hotel rooms. "Just keeping him distracted" is suppressive fire. Suppressive fire is area fire, not point fire. The notion of inviting deaths of guests in the hotel as "collateral damage" in the hope that the suppressive fire
might temporarily neutralize the shooter is about the craziest thing I've ever encountered on the Internet. Thank God the Las Vegas police don't spend too much time playing
Call of Duty.