My first answer on the new revamped News section!
OK - as always with this type of incident, looking for rational explanations is utterly futile because rationality is born of intelligence, and an ability to think beyond the standard instincts of staying alive - breathing, eating, sleeping, that sort of thing.
People who behave like this lack the basic intelligence to think about their actions, and the consequences of what they are doing.
As advised, what adults think that holding an air rifle in a room with a toddler is normal behaviour, much less cleaning it, and then 'frightening' the child with it.
These are not the actions of people who think ... at all, and should be viewed as such.
So trying to think for reasons is a waste of time - there are none.
Ideally Social Services will monitor things going forward, but with their stretched resources, you can't really hold out much hope.
So sad.