Not every day's an exhibition... or even an exemplary workout. Which is fine, because he's got thousands more workouts for the rest of his life. At his size and inexperience, I call it respectable. The body doesn't care if the weight doesn't increase... work is work. 21 reps, though... that's something to work on... From my own experience, especially when I was (still am) learning, the more reps in a workout, the better. There's neural pathways to be built through repetition, and even when they're there, you've got to warm it up and "grease the groove" every workout anyway. For me, 21 reps is usually a warmup. Something to consider, anyway.
All the same, while I was cleaning today, there was a cat that outweighed Kolton going 3x10x135 on deadlifts and wandering off to do something else mediocre, maybe get home in time to catch Two And A Half Men and eat a salad. I say 21 reps at 275 is a vast improvement over that guy's mentality.