It is extremely rare, if ever, you can get an accurate interpretation of action from a still photograph. In the video sequence, it seems clear that the defensive player was leading with his shoulder, and not attacking with the helmet, and any head to head contact that may have resulted was, in part, due to the movement of the runner.
The field Umpire would likely have been in a much better position to view the contact than this video provides, but based just on this video and the action leading up to the contact, I would not have considered this contact illegal.
