Doesn't seem like a great mix, a new puppy who needs a lot of attention and young children who need to be monitored constantly, doesn't sound very fair on the puppy to be separated off for long periods of the day, especially if crated.
I would also wonder if it would make the puppy more excitable (and like to cause accidential injury) when he is allowed around people if he has been shut off so much.
My initial reaction was the same as yinyangs, I would be interested in the circumstances as to how it happened and the level (if any) of supervision considering the age of the child.
Would it not be more feasible to have two separators eg two separate baby gates with a gap inbetween so there cannot be direct contact between the two?
I feel it is important for children to mix with animals but only under proper supervision to ensure no harm or distress to either child or animal.
My gut reaction is also that it is different when you are looking after a child as a professional service and have made certain guarantees as to how things will be done. As others have said, if this is not being followed through, I would also wonder about whether other things are not done quite as stated. Accidents will always happen but they are way more likely when things are not done properly.