so its less clean in hockey to hit a guy from the side with his head down than a guy with his head up looking at you?
I don't agree that orpik lets up at all, and he extends his arm out during the hit
A hockey player has to protect himself. The guy checking is in control, but you need to make sure that you get hit in a safe way. People putting on the brakes a meter from the boards is a typical example of risky behaviour. Keeping your head down makes it nearly impossible to get a good hit on your shoulder. Your head is going to get hit, that's dangerous.
Orpik could've picked up speed, assuming Toewes would get his head back up and take him into the boards. He doesn't. He hits Toewes and he make contact with the head, but Toewes has put himself into a very bad position and is not un-checkable. Had he turned around giving Orpik a good look at his numbers, the hit would've been bad (boarding). Toewes need to keep his damn head up.
Backes' head was up. He did not put himself into a dangerous position. He does not have the puck. Seabrook was in full control. He lifts his shoulder and catches him right in the head. That's a bad hit and he got suspended for it.
And you pretty much always extend your arm during a body hit, you shove your opponent away and into the boards. Seabrook lifts his arm up high, placing shoulder as well as elbow in line with Backes' head.