^^^ That hit close to home for me. Watching my youngest step son grow and grow through school with autism has been one of the more eye-opening experiences of my life. My dad was handicapped, so I'm sort of used to the "blindness" people have to that, but my dad was a genius, and mentally as sharp as a tack so he could fight back or not as the case may be. My step son literally thinks differently than I do (or even the rest of his family). It's been an eye-opener, especially when it comes to jokes and things like that. I'm a jokey person. I like to crack wise, and I'd much rather make someone laugh and feel at ease than anything else. That doesn't work with my step son, always. I have to be very clear with him when I'm joking, when I'm being hyperbolic, when I'm being facetious.
We live in a very, VERY hyperbolic, facetious world today. Everything is "super this" and "uber that", and we use absolute terms like "terrifying" and "dystopian" and they have taken on these practical meanings beyond the literal.
This is all to say that whether that kid meant it literally or as a barb, or a dig, IT DOESN'T MATTER. My stepson would not necessarily have been able to parse how it was meant, and it would have hurt him. And I understand your reaction to that, ESPECIALLY when it comes to the teachers and staff. I don't expect teachers to treat everyone with kid gloves, but the school staff presumably KNOWS about kids like your daughter and my stepson. They KNOW. So why do they not do everything in their power to help them be better the next day than they were today? I get teaching is tough, but you signed up for that. That's your JOB.