With the risk of contradicting myself or starting another hullabaloo, I think his position is fine. Traffic in front looks like it's stationary, he's not holding anyone up behind him and he is probably deciding whether to filter up the middle lane or hug the kerb (it looks like the van in front has left space to do this). Being in the middle leaves all his options open as long as he is aware of traffic around him.
Personally I wouldn't filter up the middle lane as the truck is right up against the edge of the lane and I'd probably have to undertake and swerve in front of the black car in the middle lane. I also wouldn't filter down the nearside unless I knew the traffic light phasing -I'd stay behind the truck rather than risk being squished as the traffic turns to the left. I have almost a phobia of undertaking large vehicles, especially on busy bends.