Why is N.O.W. not outraged and aggressively opposing treatment of women, under Sharia law?

Because N.O.W. is a far-left agenda-pusher first, and a women's rights organization second. Just like how they didn't speak out against Anthony Weiner and his sexting/tweeting obscene pictures to women. Islamists and the far-left have been teaming up, all in the name of opposing freedom and capitalism, so of course orgs like N.O.W. are not going to say a word about what their allies do.