Not saying your perception is invalid, nor trying to patronize you, but are you certain that he was talking down to you due to (or primarily due to) your sex, rather than just your apparent ignorance of the particular topic? 

To state "That's all we're asking for. Just talk to me like a person" explicitly means that person has to accept that some people will be rude and talk down to them, exactly as they do to anyone else expressing the exact same level of particular ignorance of a particular topic, right?

From talking to women in my own life, I think many women are not consciously aware that it happens to men from other men all the time, especially in fields/areas where men are expected to have a basic level of knowledge. That doesn't mean it's right, but does mean it isn't necessarily "sexist." Jerks are typically jerks to everyone, all you can do is what you did, call them on it and/or take your business elsewhere.