Okay, even using your reasoning, MLP can still be considered feminine. I think it is extremely easy to argue that MLP was made generally only to appeal to women. I mean, that's way the brony community is so fascinating to people -- it's a large amount of male viewers who enjoy a show made primarily for women and girls. If bronies were simply men who liked a "gender-neutral" show, people wouldn't find this phenomenon so rare or interesting.
MLP (a show that: features a female protagonist; consists of a core female supporting cast; primarily focuses on the role of female friendships; explores female identity; was made to sell toys and dolls to little girls; frequently mentions fashion, cupcakes, cute fuzzy animals, princesses, etc.) is feminine. But that doesn't mean men can't or shouldn't enjoy it. I think male fans feel the need to justify their enjoyment of MLP by emphatically claiming "but it's NOT a girly show!!!" But that's not true. Men just don't feel comfortable admitting they like something feminine. Men could improve society and open some minds by openly and proudly enjoying a show FOR its femininity instead of trying to insist that the femininity isn't there.
Men liking MLP doesn't mean MLP suddenly isn't feminine anymore. It just means men happen to like something feminine (which is totally fine, despite what society tried to say).