I don't think the argument is bending someone's will (we'll never get to the bottom of it lol) but that he may be aware of her intentions. If my will were bent to say, get my help on homework or 5 bucks or something and I have no clue, it makes no difference in my life and as long as we're both still well-off, leave it at that. But if I become aware or was from the beginning, that's where the karma and judgement, morals and ethics, etc, etc, come to surface.
I don't mean to propose the ''If a tree falls in the forest and no one is around to hear it, does it make a sound?'' debate on morals, lol. I don't care who is doing bad things, who is not, because she is aware of the magick she's casting and she'll be rewarded or punished in the end.
As for the spell not working, I think it boils down to focus. You have to be devoted to your purpose and pursue it with actions backed by intent.
From my perspective, we all bend to each other's will like a field of blowing wheat. It's a harmonious transaction and there is nothing wrong with getting what you want through others, so long as you can return the favor. It's when, in my opinion, that you ask for more than you need or get greedy or overly-selfish that karma and whatever else accumulates and you get punished. When wills clash is where I suppose the big issue is.