The support runner needs to be there to receive a pass or offload if the ball carrier is tackled, or if the ball carrier cannot get a pass away, he is there to ensure his team-mate is not isolated, i.e. he wants to be first to the breakdown.
This support runner was in a very good position to do either of these all the way from the time the player picked up the ball to the time the claimed obstruction occurred . While Roblev points out that he was slightly ahead near the end, that was only after the ball carrier slowed down (the support runner didn't have time to react) and the opponent pushed him in an attempt to "plant" the ball carrier into touch as well as to highlight his spurious claim that he was obstructed. The fact that the opponent sharply changes direction in order to push the support player severely undermines any case he thought he might have had.
For those who still think that this support runner was intentionally blocking the tackler, tell me where else he could have run? Note that as far as we can see, at no time does he look around to see the chasers and where they are coming from. He will be able to see the SF player coming across in front of the goalposts and will realise that this player has no chance of getting there, but the opponent who ends up pushing him comes from a 45° angle behind him; completely out of even his peripheral vision. He will have only an approximate idea where this player is; somewhere behind and to the left.
• A support line to the right is out of the question (no space)
• Running directly behind the ball carrier won't put him in a good position to receive a pass, yet he could still end up getting in the way if there is a chaser running the ball carrier down from behind.
In fact, if he really wanted to block the opponent, he would have been better half a metre further back, keeping himself between the ball carrier and the approaching opponent.
As I said earlier, if you want to apply 10.1 (c) to this situation, then you might as well make support runners illegal, because this really becomes a "Joseph Heller" situation, there is nowhere that a support runner can run that he won't potentially get in the way of a would be tackler, and we won't know if that potential is realised until the would be tackler arrives.
So, I ask again, where would you have this guy run so that he can still be in the best position to support his ball carrier, but cannot possibly get in the way of a potential tackler?