I'm just surprised at the BBM rating - in the UK it is 15, though in all the times I saw it at the movies there were never any young teens present.
However, this grandfather is a type. Years ago when I was teaching in South Wales the school "play" was "Oliver". The girl who was cast as Nancy had one of the few reliable voices allied with some ability to act and was one of the strong points of the whole thing, till her mother rang the local radio and TV stations and told them that the school was corrupting her innocent ( yeah? surprise!) daughter, then 16 going on 17, by making her play an IMMORAL WOMAN. The first any of us knew was when the progs aired.