Agreed - I have a daft cockapoo and I would be concerned about keeping him in a room with me and a baby or toddler, as I know a small, quick moving, crawling child would make him extremely defensive and unpredictable
Staffies aren't aggressive by nature but this seems extremely negligent by the parents. Apparently it was an adult dog that they bought last week. From the dogs perspective it is in a new household environment with new people it probably doesn't trust and jostling for it's place in the hierarchy...