Doing a "this you" on the internet is peak condescension. There are more constructive ways to bring up what one takes umbrage with, and by far this one is one of the most demeaning. Especially when one stands by your quote that the person is viewing negatively (and I indeed stand by it, and spoiler, I will not be changing my post).

I think the quotation marks already existing within my post make it crystal clear that "baby's first psychological horror" is entirely self-contained with its levity. The only way that someone would take personal offense at this is: A. if they view their age as a point of shame such that they read undue subtext in my post, or B. if they view their ability with the subject as a point of shame that they read undue subtext. In both of these instances, one has to take a very specific, bad faith reading of my post. In other words, I feel that this is a "bean soup" situation, which is not something I will change my post for.

I have made many versions of "baby's first [difficult thing]" jokes in my real life, in a variety of groups (and in one-on-one contexts), with a variety of ages. Not once has anyone pulled me aside for a serious conversation about this in any casual context.

In addition, I work (part-time) at a tutoring centre, where I have a "tough love" manager and am highly accountable to parent feedback (i.e. on childrens' behalfs but also somewhat their own whims); I have maybe been written up for tardiness once and never have been seriously reprimanded in relation to either my ability nor my conduct with students, from any avenue. If anything, my flaw as an instructor is my leniency (as commented in passing by my manager and other instructors). I also have never encountered issue as a university TA during office hours. I do make this joke, along with similar kinds of jokes (e.g. to a calculus learner: "this is now trigonometry, which you learned in preschool, so it should be super easy"). Notably, these audiences encompass teenagers and young adults.

If strangers on a text-based forum are saying "there are hypothetical teenagers/young adults that could be hurt by this," I have yet to encounter this once, let alone in significant numbers or enough to cause issues (until now).

Basically: why change something that causes no problems ever except to you (btw I think you're generally rather nice, we just have an issue here but other than this we're chill) and then one other person who can't help but actually and consciously deliver their feedback in a highly condescending way?