I'm not criticizing your disliking because I didn't like it too, but I think it fits her personality... If there was a girl who would do such a thing, that would be Jill. But that's the fun of the game: choose a girl whose personality appeals to you. If they were all the same, it would be only a matter of picking the most pretty of them or even going for a harem. I think this was coherent with her beliefs, whether we like it or not... The best we can do is forgive her or abandon her path... I think we have even less to complain about since MC's reaction almost fits the description of your complaints. I even reviewed the scene as a chick, agreeing with her and Burke it was bullying, and not defending Chad, and the only difference is, on the DIK route, Tremolo says: "You treated me like a fucking kid!" That is, even as a chick, the MC never agrees with Jill's actions. I think those who, in the real world, as players, agree with Jill's actions or think MC's attitude was not compatible with a chick role have more to complain about because they're not able to, as players, react the way it would be more coherent to the personality they're giving to their MC. This was, IMHO, Mr. DPC's greatest sin in this sequence (and others he denied an MC's response compatible with his affinity) and not the way he did Jill behave.
