Horobin's article indicates that Bokenham's work presents a life that all young men and women were to aspire unto in regards to morality. However, it would seem that one aspect of this kind of prompting is gender specific within the Saints lives: sexual agency.
As seen in the Saints lives the women are depicted, the majority of them, as beautiful women that are constantly battling against the oncoming sexual advances of kings, merchants, and sons of officials. This represents a common theme within the sexual agency that a women in medieval stories were inferred to have in accordance to cultural normative acceptance.
This type of discrimination would project, as seen in Margaret, Dorthy, Anne, and Agatha these women have to struggle not from within a sexual desire, but from without. These stories are displaying a type casting of women needing protection from the sexuality of others because they do not have the agency to safeguard their own sexuality. The extent of the torture that these Saints encounter emphasizes this point by the torture itself being a sexual attack based upon taking away the feminine physical attributes, thus alleviating the women of sexuality at all.
The men within the stories, however, are portrayed in two lights: one they are paganistic and do not attempt to suppress the sexual drives, two: having to advert companionship with women because they are a temptation that draws them away from God's plan. This places the blame of all sexual indiscretions on women (or the paganistic belief system that is constantly feminized in literature) alone whom, as discussed above hold no agency.
So what are we to make concerning Horobin's claim of these stories being for the edification or example of moralistic lifestyle of both Men and Women? I would tend towards these stories being a picture of an archaic belief of a woman's role within sexuality. That is to say that it projects the blame upon women for not having or holding an agency that is not allowed to them in the first place.
I like your points about how a common theme between the female Saints' lives involves external advances of sexual desire, which I think you aptly describe as coming not from within the Saints themselves, but desire that is thrusted upon them from without via male suitors. You state that these women are casted as needing protection from the sexuality of others due to their limited agency and by extension their limited capacity to safeguard their own sexuality. I find this particularly interesting when you consider the connection between internal purity and the external physical manifestation this creates in terms of beauty; given these female Saints' unmovable devotion and piety they are perceived as exceptionally beautiful with external beauty now equated with internal Christian purity. It would appear then that not only does their devotion to Christianity get them into harrowing predicaments with pagan rulers who precipitate their martyrdom, but their devotion as manifested beauty makes them prime targets for these men's sexual desires in the first place. Might the precariousness of their faith as beauty intensify them as martyrs? Given the way in which they are de-feminized through many of these tortures, and some not wishing for this femininity to be restored by God, it would seem that their lack of agency to protect themselves from the harm inflicted on them by men due to their beauty and refusal to marry becomes a passive way in which their saintliness can be established and reified. Their beauty and physical feminine traits become the sacrifice they suffer which increases their holiness. Since female gender norms of the time would advocate and expect women to be wives and mothers, this removal of sexuality becomes an important factor of saintliness in light of the true devotion and commitment through virginity they uphold for Christianity and God.