You're correct in that he had the 12v battery connected to the charger. He purchased the Prius new from the local Toyota dealer in 2009 and the vehicle was taken in and checked multiple times. As he rarely exceeded 30 mph and covered less than 3k a year, the technology was just not fit for [his] purposes. However, after his passing, taxi drivers were very happy to pay top dollar for the car, of course.
Therefore, is there a general consensus here that EVs are not necessarily suitable for occasional drivers?
No. if anything there are folk on here who will tell you that EVs are ONLY suitable for occasional drivers!
I've heard tales of the 12V battery going flat (there are instructions in my EV handbook on how to "jump start it!) if left for long periods - just like an ICE, really.