Not really? She's cold, practical and calculating, qualities quite important for her survival in that world... She didn't really degrade or said anything bad/ untrue about sumo... She just thought she could make some money out of his innocence but what did you expect? That "innocent" sumo guy walked in a brothel like it was nothing, trying to chat with a prostitute... A sheltered spoiled gullible brat is what he seemed like to me... Although to be fair he seems like a good person overall my point is he would make an unreliable ally. Considering the MC is treated like shit and knows she and most women are seen as lesser, did you think she would rely on that seemingly unreliable sumo guy to help her? Nah
And yes she's right to think of that otaku as a disgusting shity weirdo, because frankly, he is... Every time he utters a word I shiver in disgust! His ulterior motives and delusions are clear to both the MC and the readers! He's no hero, not even a bit kind and I think him getting cheat powers is undeserved and potentially harmful to the world
She's your average pretty JK who thinks oh so highly of herself, even shitting on the nice guys like sumo.
But the story's nice so I'll stay