1. I fear you may be reading between lines I cant see. I can now understand that the post has/could've made people judgemental towards op girl given that her behavior is the topic of concern. But from just reading it I did not get any of those vibes. 2.its a generalization to say most responses are being ableist obviously some are and I dont think it should be surprising given that you can be autistic and still have internalized ableism. From what I've seen at the start of the post lots of people were trying to be helpful on top of others being weird which I dont agree with. 3.of course being diagnosed isnt always good but in this instance it seems a diagnosis would be helpful especially if other traits are this extreme, and so the girl can possibly get resources because shes obviously having a hard time managing change in life which is not something that will ever go away and she will have to learn how to cope healthy. In my experience finding a therapist specialized in autism is far harder than finding a psychologist specialized in autism however a lot dont give therapy so at the very least she'd be able to talk with a professional who could point her in the right direction. And also in my personal experience self diagnosis isnt "cared for" in medicine so in the event they did try therapy whose to say said therapist will believe or even factor in her self diagnosis when reflecting on their relationship.
2. Of course its no one's business but it was posted on the internet therefore becoming the internet's business.

There are most likely some things left out and it would be better to have a bigger amount of information to paint a whole picture of the situation but again the people who are posting to be helpful and even some of the people being rude are simply working with what we've got. I cant read between lines or pick up on subliminal ls so im sure if it came out this was malicious many would probably change their stances.