I think question has several issues bubbling below the surface.
(1) Not all women are sexual. Asexuals exist!
(2) Not all women are sexually interested in men. I doubt any of the lesbians I know would seduce a man for personal gain nor would any of the gay men I know attempt to seduce a woman.
(3) Not all men are attracted to all women, nor vice versa. Just because a woman is “objectively” attractive does not necessarily mean that she has the capacity to seduce any man. Not to mention I doubt anyone would encourage an “unattractive” woman to pursue this method because this would only “work” for someone who is “attractive”, which contains within it a whole other set of issues.
However, plenty of people—and I say people because men, women, transpersons, intersex persons have all done this before—have used sexuality as a means for gains. Is this morally correct? I don’t know. I think it depends on the context of the situation.
What I don’t understand is why the sexuality of women is what always falls under scrutiny. These types of questions are very rarely framed as an inquisition for against male sexuality.