what I don't get is why the act of simply doing the opposite of what is expected of your sex, while still associating those things with the opposite sex, helps the situation - surely that's just reinforcing the binary, not challenging it? many aspects of masculinity and femininity are arbitrary, e.g. pink = girly, makeup is for women, engineering is a male career, etc.... so if a man self-consciously performs "femininity" by wearing pink and being "sensitive", it's just another way of affirming the idea that "these things are feminine". thereby reinforcing the binary even though these things aren't inherently feminine. compare that to a man who just does those things without mentioning masculinity/femininity/identity altogether. do you see what I mean?
My associations don't classify my actions as masculine or feminine, society does. The gender binary is a social institution independent of my individual assertions of a behavior as feminine or masculine. The gender binary dictates that men act masculine and women act feminine. By the gender binary's standards, if a man acts feminine, he no longer counts as a man, he falls into abjection and the gender binary lacks the conceptual resources to allow us to understand his identity. Thus a man acting feminine will never reinforce the gender binary, only a man acting masculine will. You and I both accept that the gender binary exists. The gender binary prohibits anyone from acting both feminine and masculine. If I refuse to consider my sensitive behavior as feminine, society will still deem sensitivity as a feminine trait, and it will still refuse to understand sensitive men as traditional men. Like you said, people defiant of the gender binary face negative consequences. The main penalty for acting both feminine and masculine is losing your identity as a traditional man or woman, the only two identities the gender binary allows for. Both masculinity and femininity define the male lesbian's identity. Thus the male lesbian's male femininity subverts the gender binary.