thanks to the father of the older child for posting and clearing this up.
i'm another poster horrified by the op's suggestion of segregating children. what a hideous thing to say.
reality check - accidents do happen on the playground or anywhere children play together. it's part of life. i was very precious about my first child and it's taken me some time to realise that when bigger children are playing, they often don't realise there are smaller children who might get knocked over. i realise it now as i've got one 4 year old and a smaller one!
my two have had a few bumps and bruises at the same playground. but to follow a child and shout at him or his parent?
![Shocked :shock:](./images/smilies/icon_eek.gif)
you're rather lucky the father involved here had such self control, as i would have been less civil to you in similar circumstances.