Even if the woman’s rabbi gives her a heter (which seemingly is only applicable while on a date in any event), the employers rov may not hold of such a heteirim and he is forbidden from seeing her with uncovered hair.
OK. And? (seems to be a theme today). It’s still illegal, and still Mutar for her (the two questions asked by the OP). Maybe to be nice she can do so if she wants, but by asking, the boss opens himself to a discrimination lawsuit.