The father of this young child only had the best intentions for his child.
Safety and their well being should be the crew’s first priority, or so they remind us.
Imagine RTO with evacuation, or depressurising need oxygen,
the child is alone and in need of assistance, he did not see the preflight briefing from his low eye level seat,
and can not understand the takeoff briefing card.
It is the crew’s responsibility to ensure children are safe and not left alone. Not separate them.
Children are your future customers, treat them as very important customers, good airlines provide colour pencils and books etc.