"...feminism is not just about advancing the cause of women. It's about advancing the cause of a just humanity."

Wrong on both counts.  It's not called "humanism" or something similar, it's called "feminism", for a reason.

When feminists become as concerned about the paucity of male teachers, nurses, dental hygienists etc. as they are about the paucity of female engineers and software programmers, only then can you legitimately claim that feminism isn't just about women.

When feminists stop claiming that men's 3-4 fewer years of life is an "advantage", or that law-abiding men should pay higher tax rates than women because most prison inmates are men, only then can you legitimately claim that feminism isn't just about women.