I’d be shocked if your explanation wasn’t the real one. “Optimized for writing” sounds like the sort of justification you give when your project with a sarcastic self-deprecating name becomes surprisingly successful.
If they wanted to name it after a fast, efficient famous writer it would be Apache Hemingway.
Kafka died before most of his writing was published and most of it was destroyed, which doesn’t seem like something the software would want to be associated with, right?