I think sexist is too specific, since as you pointed out he's essentially a racist or "clanist" (not a real word). The man is a bigot, so that he's a sexist seems to stem naturally from that as would any other type of disgusting discriminatory remarks and attitudes.
I wonder though how much of factor Uzumaki Mito is a factor in all this. She was the one who intervened when Hashirama gained control of Kurama during the fight at the Valley of the End and sealed it. Further, both Tsunade and Mito have a physical resemblance such as the diamond chakra seal on their forehead among other things, such as would result from her being her granddaughter.
As well, ET Madara is from an older era of say maybe 100 years ago, and I think that that may be a factor. He's also got the sinister chakra, and is so full of hate. I don't think it can simply stop at sexism; rather, I think sexism is a byproduct of all the other things that define him, his dark and sinister chakra, his hatred,..., and his bigotry. He's reviling,..., truly evil. Thus, he's well remarkably well written by Kishi, although I do wonder what Kishi must feel when he's writing the lines of ET Madara. I don't know how I would feel except that I would be delighted being able to write the lines of Tsunade at the same time at the end, with her coming back with her "Will of Fire" statement!
:izuna: :izuna:
Peace