I actually think he tried to head it. He didn't get down fast enough and the ball glanced off his head onto his arm. Unless he's trying to impersonate Lizzie Yarnold his arms weren't going to be anywhere else. It was just unfortunate. Had he not tried to block it and Shaw scored, what's the odds he would have been criticised anyway.
Oh he definitely tried to head it. It was just too low for him when it got close. He didn't have a lot of time to get himself set for it because it was a hard shot and he couldn't get into position for it fast enough.
I was fuming about it when I saw it but I play center back and I've done what he's attempted to do their before. Your instinct is to get in between the ball and the goal when you can, sometimes your body doesn't move as fast as your brain does and you give away a deflection or a handball like in this case.