I think without placing this within the context of separatism you get side tracked into thinking it is about chosing one's sexuality.
Many women led a separatists life, without necessarily going as far as setting up a separatists commune.
However choosing to have as little to do with men as possible because so much time and emotional and sexual energy went into propping them up, was the political choice.
Whether from that you then chose to be or have lesbian relationships or become (politically) celibate was part of that politics.
In fact at one time there was a move that all women should wear a badge saying "lesbian" to make a statement to men that as a woman you weren't sexually available to them.
Women's Liberation politics wasn't about "choice" feminism, it was about a lived experience.
And in fact when you look at the number of women who come out as lesbian later in live, its hard not to think that most women identify as heterosexual because that is the default social pressure. Not only to be sexually available to men, but to become pregnant! ie if heterosexuality is compulsory then to chose not to do that is a political act against the class of men.