Kathy,
Talks one thing, action is another. Has this hypothetical person a history of commiting serious violent attacks. If not, I wouldn't be to worried, his chances of meeting a 'ET look a like' are pretty slim.
Delusional people are not violent, angry, violent people are! If theres a history of violence then the trend will probably continue. If there is no history of violence then that trend would probably continue.
Moreover, when I was a young man being treated for SZ, I was well aware of the stigma associated with SZ and I used it. If my folks were giving me a hard time, telling them a story similar your scenario would scare them enough to get them to back off. I was just using my diagnosis and making up symptoms as a form of teenage rebellion I suppose.
Still, it usually back fired because my folks told my shrink, which resulted in more punishment (more meds).
Do you know what I mean?