Is not only the fact that she is a woman, is the surrounding context of a sexual stimulation device that provoque so many upvotes. Personally I would downvote this if I could, I don't like my tech articles biased by hormones.
In fact, the only awkward thread, which seems a little sexist is this one... Food for thought.
But in this case I think you're wrong. This thread is a totally legitimate discussion of a very interesting, detailed and inventive technical post and I find it hard to believe that an equally detailed and well-written post from a male perspective would not be received in much the same way.
I don't think you're being sexist, but you are being wrong about something in a way that an average internet commenter would find hard to distinguish from sexism (and the average internet commenter is not particularly capable of nuanced thought).
I can only assume that you are very naive; for the average male is impossible to read this article without imaging a woman using the device; wish does not mean that there aren't legitimate and interesting discussions in this thread; but is clear that the exponential popularity grow of this article is strongly correlated with that fact.
For example If a boss needs to hire a good secretary for one of his employees; and assign him the task of finding one and then tells him "Don't let your hormones decide for you" is pretty clear what he means; that sexual attraction and gender should be irrelevant in the selection proccess and he should focus in practical skills a secretary should have. And there is nothing sexist about that; because sexism is discrimination based on gender and this is an enforcement for the lack of that kind of discrimination.
Also, why does it have to be a secretary? Are they 100% female now? If he was looking for an engineer, would he need to be told not to let his hormones decide?
The majority of secretaries are female (not all); and is no secret that sometimes people hire based on looks instead of actual skills.