As always with this question, we ought to be asking whether the women who work in that place have the privilege (privi-leg, ha ha) of going around with bare legs when the men are required to wear long trousers. If that's the case, maybe it's fair if there are limits to women's extra freedom, as in "Female employees may wear skirts without stockings, but must not allow leg hair to be visible." When your legs are covered, nobody will know or care who shaves and who doesn't. Put them on show, and some people might make it an issue.
But hygiene, no, it's nothing to do with that. Social conformity (for woman and men) is what it's about.