A Kantian moral duty for the soon-to-be demented to commit suicide

It has been argued that, on Kantian grounds, pedophiles, rapists and murderers are morally obligated to take their own lives prior to committing a violent action that will end their moral agency. That is, to avoid destroying the agent's moral life by performing a morally suicidal action, the agent, while he still is a moral agent, should end his body's life. Although the cases of dementia and the morally reprehensible are vastly different, this Kantian interpretation might be useful in the debate on the permissibility of suicide for those facing dementia's effects. If moral agents have a duty to act as moral agents, then those who will lose their moral identity as moral agents have an obligation to themselves to end their physical lives prior to losing their dignity as persons.