It's not a fringe theory. A lot of people have discussed how her assistant likely made up everything.
I have seen a blind/deaf guy "write out" a destination on a bus drivers hand with his finger, and the bus drive did write a response letter by letter once. The bus drive tapped his shoulder at his stop. I doubt the guy was entirely blind/deaf. He had to see/hear a little bit I'm sure.
@djsumdog@justnormalkorean The most suspicious part of the story is how she learned a system of communication that only her assistant knew and had apparently been made up in a few months; that, and how such a supposedly intelligent woman possessed an equivalent political worldview to her assistant.