Bruce, regarding your belief that the dearth of women participating in open source is primarily due to lack of interest or aptitude, I'd like you to come for a thought with me.
You say that you have had women and gay men cause you to feel uncomfortable in the workplace. I ask that you use that experience to conduct a thought experiment:
Imagine that your industry has 98% female participation. These are the women who made you feel uncomfortable only, on average, they are stronger, more arrogant and more notoriously horny than you are comfortable with.
Imagine that of those 98% 4% are overtly misogynistic and hostile, loudly mocking of your contribution, males in general and you, personally. Only a few of the other women ever spontaneously chide them and ask that you be treated fairly. 80% of the women don't even notice the bad behaviour.
Imagine also that your overall impression is that about half of the women you have ever worked with (still the mooted 98% of all workmates ever) have been overheard making casually derogatory remarks about the sexual proclivities of men -- specific and general -- and some of those comments have been made about you, personally. Your objections are dismissed as irrational: you should be a "good sport".
Sexually explicit questions are routinely asked of you directly, by women you are trying to work with, in any form of media with which you communicate. Some of the women are unnervingly creepy and persistent, and get disturbingly hostile when you do not respond as they would wish.
Imagine that suggestive to semi-pornographic images of impossibly handsome men, and lewd "clever" captions are used widely to promote the product you are working on. Imagine that when you suggest that the imagery is not cool, your teammates tease you, deride you, ostracize you and talk about how uptight you are behind your back.
Imagine that whenever you arrive at an industry conference some harried organiser snaps "Deliveries around the back". Once they let you in, a few people will ask you who your partner is (you must be accompanying a woman because men don't work in the industry), and almost everyone who does not ask makes that same assumption.
Imagine that walking into the conference involves wondering which of the women there -- women you are not attracted to, do not know and only wish to interact with on a professional level -- are the 4% who have nothing but contempt for men. Who are the 50% who see men in your industry as a bit of a joke? And who among them are going to try hitting on you over the course of the conference? And, when you decline their unwelcome and inappropriate advances, will they graciously accept 'no' for an answer? Whether you say yes or no, will they lie or exaggerate to their friends, to your cost?
Imagine the appeal of asking a female friend to accompany you to such an event so that you don't feel like a gazelle in a lion enclosure? Can you imagine the disgust and despair you feel that such a precaution should even cross your mind in such an honourable, well intentioned field of endeavour?
So, Bruce, how good is your imagination? How long would you tolerate marinating in that before you could not be bothered volunteering your spare time and earnest efforts any more?