Also, I perceived the joke to be making fun of the elderly, not women. Honestly, you post seems like you were primed & ready to be offended by the slightest thing, which has more negative social impact than the light-hearted title of the linked article.
If it wasn't historically pervasive, yet false to declare that women are not tech savvy, I likely would not have said anything, however, this is a technology focused community and thus it seems relevant to not promote that unfortunate typecast.
I was unaware that Moms were considered elderly - I had my first child at 25, is that old? I guess that's another case in point why not to use 'Mom' in this sense, it comes off insulting to some and also is perceived to mean multiple, possibly unintended things.
Look for ways to be offended, or look for ways to understand. You seem to be doing the former, which is wasteful.
I fear we are entering the spiral of pointing fingers at one another.
As a mother and thoughtful human being, this is when I would suggest to my children they walk away from the situation at hand and I will thus follow my own advice.
Also, the person to whom you're responding had, when you wrote this, one carefully worded comment on the thread. "Primed and ready"? Clearly, the person on the thread most fitting that description is you. Please stop doing this.