There are very few cases where I would agree with you on this. Considering this person doesn't seem to be distressed by his experience I don't see any reason for them to seek therapy. I suggest reading up on The Hearing Voices Network and perhaps checking out the book Rethinking Madness.
Somewhat off topic, but I recommend checking out the following (non-Scientology) books which might help you understand what people with some types of dementia may be experiencing. Often people reach out to things like Scientology because they lack people to talk to that they can actually relate to their experiences - or even people that will listen with an open mind.
Rethinking Madness by Dr. Paris Williams - this is an academic quality work, btw, not some crazy person rambling (that's important to me)
Hallucinations by Dr. Oliver Sacks - a neurologist who has written several popular books about unusual neurological phenomena
Before throwing things like that out there you should get up to date on current literature within the field of psychology. I recommend checking out Rethinking Madness: Towards a Paradigm Shift in Our Understanding and Treatment of Psychosis