It's hard to say from that still, but it's plausible he may be trying to lean over that enough to bring his left eye on the scope. The P90's ambidextrous too, he could swap it around! Hahaha. But, Devil's advocate:
There are lots of continuity and other errors in the show, but when that scene happens he's been blind for what? A week or something? Next time you're out shooting, totally reverse your stance, grip and sight picture and compare that to keeping everything the same and just covering your strong eye. I'm betting you do better leaning over and using your weak eye, at least until you've totally retrained yourself otherwise.