nina not a daft question. Plenty of grandparents, aunties, uncles etc bring up relatives' children without any involvement from Children's Services. As long as there's no risk from a family member and everyone agrees that's all fine. Children's Services presumably became involved in this case because the mum had mental health problems and wasn't well enough to look after her child, she didn't agree to her parents doing so, and Children's Services then had to go to court to get a decision on the child's future. For reasons we still don't know, despite the tit for tat reporting, the grandparents were ruled out by the local authority at an early stage.
I think it's good that they will now get proper legal representation and the case will be heard by a Family Court judge - I can't think of anyone else who could decide at this stage in the proceedings. In my experience Family Court judges are usually very experienced, sensible, and often pretty confident about not blindly following recommendations if they think assessments have been flawed. No use speculating any further IMO.