He looked down because he lost the puck in his feet. This shouldnt be this hard to understand. He also has no time to brace for the hit regardless as Wilson was on his before he even finished his board battles.
Okay? It's not hard to understand, we're both seeing the same event. He did the wrong thing. If you lose the puck in your feet along the boards like that, get your head up. This play is right off the dump in, there are other players coming. You essentially lost your chance at the puck when you didn't get it clean, and that's not your fault, but the next step is to look up and get out of the way of/absorb what's coming in next and then battle until your own support shows up.
It's not an uncommon play and it's how a lot of 4 man shuffles on the wall start. He doesn't have enough time to brace for the hit
and keep the puck, but only if the hit is coming and that's important, because it was. If it wasn't he still had time to check first and win the puck against Vrana, he had done that much already. He did too much too fast, skipped a step with confidence, and took a shot for it because it
was coming and nobody seemed to warn him.