And it'd be different had the MU Terrans of Archer's time been light sensitive, then you could more believably say that Terran Empire scientists had cured the photosensitivity with medication or by altering the human genome between DSC and TOS, but Mirror Archer and the other characters aboard his NX-01 and the Defiant were walking around and functioning under the same lighting conditions as the rest of ENT as well as TOS.