QB is just different even if running cannot hit him like a RB or WR.
That isn't the case. A players position has nothing to do with targeting, rather, the determination is made based on the action they are performing. For example, being in the act of catching a pass, kicking the ball or what applies to QB's most often passing the ball or sliding feet first makes you a "defenseless player". The only time it matters if you are a QB is after a change of possession (so that people don't just go hunt the QB after a int)
Targeting comes in 2 forms:
1. Forcible contact anywhere on the body with the crown of the helmet with an indicator of targeting (dropping your head, crouching and exploding up into the head, launching or leaving the feet). In this case it doesn't matter what the other player is doing or if they are defenseless.
2. Forcible contact to the head or neck of a defenseless player with an indicator of targeting. Defenseless players are as listed above. So they player being hit has to be clearly defenseless, the contact has to be to the head or neck and there has to be a indicator of targeting.
In the case of DO, he certainly doesn't meet the first definition since the contact was with the facemask. Based on Sark's post-game comment, the QB was deemed defenseless. I don't see how. Had be been throwing a pass or even standing ready to pass and looking downfield - he may be considered defenseless but as I pointed out, he is pulling the ball down and attempting to scramble. The contact was definitely to the head of the QB so we meet that criteria. I also fail to see any indicator of targeting from DO.
tldr; DO should have his penalty reversed.