So Isabelle is trying to make it seem that Jace actually sees Hodge as an authority figure, and/or will actually punish Jace for stepping out of line when it been shown not only here, but back in chapter five that Jace actually does whatever the hell he wants, with little to no negative consequences. Remember when Jace admitted to putting a rune on Clary, and bringing her (who at the time was thought to be a mundane) to the institute. Yeah, Hodge yelled at him, but other that he just basically gave a slap on the wrist and let him go own his merry way.
Now, add this second snippet where Jace eats Hodge’s food, even after reading the note that was left on food container that told everyone very plainly not to touch it. I have never seen a teenager get away with so much shit as Jace Wayland. I am of the opinion that it’s not Hodge that is ruining the institute in the Lightwood’s absence, it Jace. So in the end, why is Hodge even here? To be yet another Deus Ex-Machina character, when we already have at the least two other characters (Luke and Dorothea) who already fill that function.