I agree with the "move the obstruction and which way would the dice land" logic, and I think the casinos look at it this way as well. But in the picture above, the dice is pinned between the wall and the other dice - so which is the obstruction? If you move the wall, you get a 7 as you said. If you move the other dice, you get an 8. I think this should have been a "no roll" if the roll in question exactly matched what La$Vega$ has recreated in the photo above.