If someone is that sensitive to light and requires absolute darkness to sleep they should probably just get a better eye shade. The plane is a shared environment and it isn't reasonable to demand no one be allowed to look out the window just so a couple of people are apparently vampires who can't stand a single lumen to disturb their beauty sleep.

Window shades and seat reclining seem to be areas fall into two camps. There's the "screw you, got mine" camp who believe that everyone else must comply with exactly how they want it. And the "we're all in this together" camp that understands that you aren't going to have everything perfect in a cramped, crowded environment like a plane and you've just gotta accept that and put up with it.