Normally at FR humor about the quality of pubic schools is welcome.
It is when under stress (lack of sleep, etc.) that a person’s character is revealed. Put another way: it is always good advice when feeling a bit whiney to lighten up, reach deep inside, and not allow a lack of sleep to cause oneself to be sour and humorless.
In that case, a “:)” or a “;)” at the end of the public school remark would have been a clue that it was intended to be humor.
Put another way, it is advisable when expressing one’s thoughts through a medium in which there is no availability of tonal inflections or facial expressions to use whatever is available to make one’s intention - dare I say? - clear. That way, the speaker doesn’t feel compelled to reach down into himself or herself to conjure a further insult to the “listener” by challenging his or her character for failing to read the speaker’s mind instead of merely reading the words placed before him or her by that same speaker.
As for public schools, I’ll wager most here attended them.........decades back when a public school education was still meaningful and advantageous to a student’s future.