In the frame Murray actually looks behind the centre back (let alone level). Also as Bennett's right foot is not on the floor and I would guess at about his hip level it is not at the actual point of contact on the ball and if that is the case and because of the nature of Murray's run it would suggest he was even more onside.
Still all conjecture. I think it is safe to say we have got no help from linesman against Bournemeouth this season.