This is a fantastic question and I believe it was both. They didn't want to use a label associated with a Nazi sympathizer, but also "Asperger's" and other functioning labels over-simplify the experience of Autism.

People with so-called "high functioning" Autism are assumed to be "high functioning" simply because their external presentation is less obvious. However, this doesn't mean they don't struggle immensely internally.

People with so-called "low functioning" Autism are assumed to be unintelligent because their Autism is more obvious, or perhaps they have co-occurring disabilities with are more externally obvious.

Yet people's ability to function will vary day-to-day depending on the circumstances, context, environment, support/understanding, as well as other factors such as health. Autism is dynamic, not static.

https://medium.com/neurodiversified/autism-levels-are-still-functioning-labels-f18ce20528dc