Why is this decision being made by someone who doesn’t know my children or their swimming ability?
Pool operators have a legal responsibility to ensure the safety of their customers as far as is reasonably practicable. They are required to carry out a risk assessment and put in place appropriate control measures.
They cannot pass that responsibility on to anyone else or be excused that responsibility by the parents. Even if you didn’t sue in the event of an accident, they could be prosecuted in the criminal courts.