I was accused of using AI in my dissertation but I wrote it all myself

I am specifically talking about Aspie and not other places on the autistic spectrum. (You would be one; I am not.) But otherwise, yes you are correct. However, note that it is not just the mechanical feeling of perfectly executed prose, but the mechanical feeling especially of imperfect prose that tends to come off as LLM-ish to some people. Specifically, imperfect Aspie prose is somewhat distinct and also may feel somewhat similar to LLM prose to those who don't have tells to distinguish the two, because the mechanical structure becomes more obvious, and one of the tells of LLM content is sloppy or awkward phrase usage or word choice, which is common from Aspies that are still learning. I tend to see that kind of prose like Scratch blocks of phrases they have learned. Once you know how to spot it, it is fairly obvious and distinct from pure LLM, even if LLMs have an otherwise mechanical output. The reason it's specifically Aspie writing that tends to get mistaken this way is because even other types of autistics don't typically learn to template whole phrases and sentences this way, so they tend to produce different kinds of flaws that are not as LLM-ish feeling.

It's less work than doing it over again for sure. People lazy enough to be efficient in the first place will typically do some work to avoid even more work.