You just made an important logical error. You went from "I can't see X" to "X does not exist".
As a fellow guy, let me tell you: it is much harder to see something when it benefits you than when it hurts you. You may never notice two steps up to enter a building -- unless you're in a wheelchair. So you should never assume that sexism doesn't exist just because you haven't noticed it yet.
And your qualifications for being able to make this decision for us all are?
They wouldn't stop using the bot when she asked them to because it made her uncomfortable. It's been pointed out in these comments that she could have sued this company into a hole in the ground with a chat log and that fact. I think "Judge will probably say it is" says it's sexist.
That's not how logic works...
I don't mean to be condescending but, when a word has a specific definition, it's pretty straightforward to determine whether or not it accurately describes a situation. Consider it like a mathematical proof: credentials, judges, and everything else are irrelevant if you've shown the word doesn't apply.
The case is lost. You don't find many who would even bother to think about what you are saying, you will be just down-voted by knee-jerkers, who cannot be bothered by contemplating what is sexism, what isn't. They just know what's not acceptable and act accordingly.
HN is humor free zone, no matter what kind of humor that is.
Other people are saying the joke is sexist, I'm saying it's not. That's all.