I don’t think that’s quite it. She’s saying that the immoral man doesn’t accept that “one ought not to X”:
In saying “he sees no reason to obey its rules,” I take her to be saying that the idea of “ought” makes no sense to him, or at least for him. So, as she says, he isn’t being inconsistent.
Talking of inconsistency leads me to another comment about her starting point, which is very dismissive of Kant. She says:
[M]any, for instance, agree in rejecting Kant’s derivation of duties from the mere form of law expressed in terms of a universally legislative will.
. . .and that’s the last we hear of it, at least so far. But in fact Kant’s version of what a categorical imperative might be is one of the few I’m aware of that deserve a close look. Kant does say that it would be inconsistent for the amoral man to see that X is immoral yet do it anyway. However, his inconsistency is of a peculiar type. It is a formal inconsistency, and Kant believes there are at least two types of contradiction involved. I don’t want to go into all that, because at the end of the day I don’t think there’s much force to the idea that “you should be moral because you contradict yourself if you aren’t.” I’m just pointing out that what Foot calls “mere form of law” is actually a strong and original attempt to forge the “is - ought” link.
Also, Kant made a big contribution to showing how ethics must involve universalizability. One may not agree that there could be such a thing as a categorical imperative, but the content of what Kant believes such an imperative says – the “maxim for everybody” idea – is extremely important.