Bit late for my comments on here:
But VA had to make do with what they could.
The kids were in the most secure place possible, in the circumstances.
Not every tom, dick or harry could get into domestic secured zone, as security would have closed for the night at MEL T3, so no one could have gotten in after last flight had departed.
Not sure/most likely, VA staff would not have a working with childrens cert, so they would not have been able to be in the same room as the kids for the lenght of the night, so it (the VA the Lounge) would have been the most appropriate spot.
If the/a VA staff had taken the kids home, with them, it would have been blown up into a big huge explosion.
Not the ideal, but I see VA had to make do with what they had access to, having the kids in a place, no one else could get to easily, and there would have been video surveillance in the secure zone, so if the kids had gone out wandering, there would have been video evidence of them doing so.
Will turn my Waffly off now.