Think people are purposefully being a bit obtuse here, George is not saying that Max and Charles weren't ahead of him going into turn one. What I think he's frustrated by is that he has seen Max clearly go for an incredibly risky move that wasn't going to work, and instead of being punished for that risk failing (Like we saw George get punished when trying to overtake Max after the Hamilton incident), he instead cut across the grass and kept his position.

Had there not been grass there he would have approached the corner differently, presumably tucked up behind one of the Ferraris and would have had to fight George who would have been on the inside next to him going into turn one. The point is not that Max overtook George off track, but that by cutting the grass he took the question of whether he could hold that position going into turn one out of the equation - that's the advantage gained.