email was where you observed the behavior you made fun of, but you may not even know that I saw your making fun of it elsewhere. it was public, but not a forum I participate in. and it's not like it seemed, it's like you were, but I have no reason to think you thought of it as a disability. heck, I don't even have a name for this fuzzy perception of time in the past, by which I perceive things as "just the other day" or "a long time ago", having little clue as to exactly when things happened. it leads to embarrassing mistakes when I go by otherwise faulty memory, and, as I said, I didn't make much of it in itself, but making fun of it in public in a gang didn't fit with the notions of promoting inclusive, tolerant and respectful behaviors. it was rather cheap, cruel and hateful.
see, it doesn't matter whether you perceived it as a disability. ridiculing someone for a mistake, for ignorance, for a disability, for a different cultural background, is not any cooler than doing so for sexual identity or orientation, for ethnicity... the difference is that some of these are more socially tolerated than others.
same goes for endorsing a cancellation campaign over intolerance to characteristics related with disabilities, and incomprehension of differences in perceptions of context, meaning, and intent. it's no less hateful just because you don't know or don't understand enough of these things to know better. there are terms for that: prejudice and intolerance