Earlier quoted context omitted.
How is this different than a gender swap in a non-vr game? I'll have to join vr chat as a girl tonight and see how things go. That said I normally play star citizen w/ a female avatar, and other than thinking "the person I'm talking to might think I'm a girl" my mindset doesn't change much...
Maybe looking down and seeing big breasts (assuming that's the case with Alyx) triggers something uncomfortable in a male's brain. Maybe we can feel like what it is to be trans and feel that your body "isn't right" for you.
You can look down and see them, but they're not egregiously large.
Though one of the funniest bugs (feature?) will only happen if you play with a female avatar: if you lay down in a bed, and then open up your mobiglass (in-game arm-tablet-thing) the UI lands about halfway through your breasts. It's like your character places their arm on their stomach, and the UI is projected forwards towards their face.
If I remember to I can take a screen cap of when it happened to me the other day on stream.