Being declared legally incompetent is more than just knowing right from wrong. It is also more than assuming or proving mental illness.
From Cornell Law, incompetency is: "1. Lack of legal ability to do something, especially to testify or stand trial. Also known as "incompetency." May be caused by various types of disqualification, inability, or unfitness. Someone who is judged incompetent by means of a formal hearing may have a
guardian appointed by the court."
IMO talk about LVD "faking" incompetency proves to be a disservice to those professionals who have worked with her. It presumes that she is smart enough to outsmart those who have spent years studying what does or does not make someone competent.