It's fitting out of how the disrespectful and cocky manjuu is demanding stuff and auto proclaiming being awesome for doing something that nearly all the marisas do, like if Reimus demanded sweets sweets for using both their brads to do random stuff.
Though i would be honest, i would call it scum as much, shithead is only fitting since we lack the "scum" tag. But while clearly arrogant, she hadn't said any of the magical shithead words yet.