It doesn't attempt to say that the gender divide is the cause of anything. The theory is that women are less risk-taking than men, that we should see a lack of women wanting to participate as evidence of increased risk: Evidence of rather than causation of risk.
The problem might be either:
1. Bitcoin is not a bubble, and this wealth transfer ends up benefiting some males substantially.
2. Bitcoin is a bubble, and the people arriving late to this party might end up being bag holders (women and men)