Why would pedophilia be considered a disorder but not gerontophilia?

Don't know: Various diseases and conditions are established by professional groups. New categories are added from time to time. If you fee this is an oversight you can contact the american psychiatric association and ask that this be considered.

Matter of consent: If someone were only/predominantly sexually attracted to elderly who are too demented to give consent, he or she would also be considered emotionally disturbed, even though there may not be a term for it in any commonly accepted psychiatric nomenclature.