I’m with Ben. Backstop as an excuse is a clear tell the individual did not have the confidence the utilize a patrol rifle. That being said, the LEO should not have been armed with a rifle to begin with.
Even using iron sights, it’s fairly difficult to miss an adult-sized target at 300 yards. That’s generally the minimum marksmanship requirement for all the services.
I would love to attend a range session with you and let you show me how easy it s to hit a target at 300 yds