That's the problem with this rule - targeting can be really subjective.
The biggest problem with this rule, however, is the ball carrier takes a lot of blame in some situations. For example, a player got ejected earlier in the season (I believe he was from Oregon) for targeting. If you watch the replay, the defender went low to make a tackle and the ball carrier (a QB) began to slide to avoid the hit, and it happened at almost exaclty the same time. The defender had no physical way of changing his trajectory, hit the QB hard and got ejected for targeting. It was total BS because the they both began to make their respective football moves at the same time, and had the QB stayed upright, it would have been a clean tackle.
I didn't think SJB's hit was particularly egregious. Of all the "targeting" hits I've seen, and all the hits from previous years that they're trying to do away with, I would only rank his maybe two or three on a scale of 10. The problem is he led with the crown of his helmet towards another player's helmet.