This case is an extremely simple one.
1. There was no urgency nor emergency caused by these children, the captain should have been very careful in getting involved into this scenario and delegate his decision to the company security officer.
2. If there would have been an evacuation and those children came of the plane alive they would have been very happy.Foot injury or not.
3. If after an evacuation this issue came ever to court it would take years of discussions amongst experts that very likely would never find an end.
To take the decision to delay the flight looks a bit silly to me and a clear overreaction. There are certain things you keep away from your corner unless you are the real macho type.
Decision making is often a case of probability assessment, once you corner yourself in a case of very low probability you loose credibility and you get sucked into something unreal.
What about banning Muslim woman to wear a veil in case….
Company policy makers do not think of every scenario, it is not human to expect them to do so. Therefore it is unreal to conclude that; since it is not clearly on paper that it is not allowed to assume that if the problem would arise, a decision by the airline would be made on the spot.
If a dubious case like this does arise, there is nothing wrong with getting advice from higher up and cover your ass.