I’m at a loss to see how keeping sick people away from children costs children’s lives. Are you perhaps engaging in an attempt at liberal logic?
When you restrict travel with a quarantine, it costs.
Perhaps you restrict a sick child from going somewhere else where they need lifesaving care.
Perhaps you prevent a child from escaping an abusive situation.
Any economic cost is potentially fatal on the margins.
If the quarantine only saves one life, it may not be worth it.
There are enough people with severe adverse reactions to vaccines, for example, that you have to balance costs and benefits.
It is easy to consider obvious benefits and to ignore less obvious costs.
I was pointing out the human tendency for that.
In a way, it was a parody of liberal logic.
I am wary of any argument that says "If it just saves one life..."