If the underwear bomb is visible on the WBI, a sanitary napkin is too. That brings up the first point, which is that I am not comfortable with being imaged to that level of detail. The second point is that if a sanitary napkin is visible, are they going to ask a TSO to visually inspect the person every time they see one? (Paolo says you can tell the difference on the WBI, but I don't see how you could. This is technology that outlines surfaces.)
Actually, maybe they should start visually inspecting menstruating women. That would bring them down fast!