If he were shooting something bigger than 5.56, then you'd want to try to seat it more firmly in your shoulder. An AR-15/M16 generates pretty negligible recoil, so it's fine. I used to compete in across-the-course service rifle when I was much younger (before I grew up enough to realize I hated the culture in that community), and I'd have the butt even higher up in my shooting coat's shoulder if I needed to do so in order to get a good cheek weld. At a glance, his technique looks okay. I've no experience with the front grips like that (my AR-15 had no rails for mounting shit), but the rest of his stance seeeeems okay.
I'm guessing that he was a dipshit in other ways and this bad publicity brought the other badness to light.