Seidenbergs intention wasn't to hurt Toews. Toews slammed on the breaks right before contact. Looks like Seidenberg was going to try and pin him on the boards while lifting Toews' stick to get the puck, which resulted in Toews hands going up. When Toews put the breaks on, Seidenbergs moment plowed him face first into the boards. Had Toews kept going around the corner, it would of been shoulder to shoulder.
It's just an unfortunate play and 2 minutes was fair. I do think players need to put themselves in better position, especially along the boards and not have your back to the contact like that, but it was a quick play and happens.