Unless, of course, he's really a VPC operative giving anti-sniper weapon fodder to the gun grabbers. In that case, he can villianize .223 varmint rifles at the same time they villianize everything else.
But a person who was a trained sniper would KNOW that .223 pointed away from a trained sniper. And would know that .223 was "good enough" for this purpose.
That said, I'm dubious this person is a professional sniper; certainly doesn't seem to be required by the evidence.
He would if he didnt want people to think he was a trained sniper. Why use the standard tools of the trade, and give himself away?
Be thankful he is not using a .50 cal...