A thought occurred to me today.  I have been around people who suffer "dementia" which is a pre-condition to the onset of Alzheimer's Disease.  Often times with these conditions patients suffer periods of "disorientation", they "go back in time-remembering ALOT from childhood and younger years" and they often cannot recall the "short term-memory".  It is particularly WORSE when "isolated or alone".  Patients suffering from Alzheimer's or Dementia can do well around people (or on a set, or work, etc) because they are around people, they are being TOLD what to do.  Often times the "illness" kicks in at home and shows up in lack of hygiene, forgetfulness, disorientatioin, not eating right, just do "out of the ordinary and bizarre" things.  Perhaps, when everything else is ruled out, it would not be uncommon for a man in his seventies to have Alzheimer's.  IF he did indeed perform this act, he may have been "disorientated (remember he did NOT show up to eat), he had some confusion, he was alone, and perhaps as a younger man he performed this type of "sexual act" or may have always wanted to...and he was just NOT a right or normal state of mind.  Something like this would NOT surprise me if indeed he sufferred Dementia or Alzheimer's.  I have had experience with these type of patients and this is something they COULD possibly do, without REALLY knowing what they were doing.  They were in a state of confusion, memory loss, and honestly it was just "pure innocence"  of a person just "growing old".  It was the "disease" and NOT the person.  Something to think about!