Is it fair to you? No, it isn't.
However you need to realize that _that question_ has been used, probably verbatim, in bad ways against her or her peers... therefore she has pattern-matched this into a sexist question too.
This is not an irreversible state. 99% of these communication breakdowns can be solved with a polite correction: "no, didn't cross my mind. I am sincerely curious about what drives that career decision, if I may ask".
I won't get entangled into a straw-man battle-royale, so if the person cannot recognize they made a mistake and correct course: sure thing I'll retreat.
That hasn't happened to me just yet, but I know it could. Fair? No, but it is what it is.
I am aware we are dissecting a quickly summed-up situation here, so my argument might not apply to the actual encounter you experienced. But if it does, I think you and lots of others are skipping on conversations that you actually wanted to have due to a very small and temporary defect on the dialogue.
And how do you know? You have direct knowledge of it or are you just pulling out a factoid?
But then I also am not part of any minority group. I'm a white male in a western country who is good at what he does, which would let me incur a lot of awkwardness before someone thinks that the problem is me. That might be different in your situation, or simply in that context, I don't know. Regardless, it makes me sad that there was a need to bury the topic.