She has also kidnapped him several times, forced him to fight monsters near the edge of his ability and likely lied to him on several occasions.
That's not to say she hasn't been helpful, only that her methods are deceptive and often violent.
Noemi OTOH might also be trying to use him, but her approach comes from the other opposite extreme. Passive, harmless appearing, and overly friendy.
I have always been a big proponent of hearing both sides out, and would like to at least have the illusion of making my own informed choices. At the moment neither side is really being all that forthcoming with info, but Elllen has so far forced the MC to follow her lead rather then letting him do so of his own free will.