I side with the parents on this one.
The parents are idiots for refusing the transfusion but they are within their rights to do so and suggesting otherwise sets a bad precedent.
What if instead of a blood transfusion it was a therapy which has only a slim chance of successfully curing the affliction but major short and long term side effects? Should a parent who declines to subject thier child towards such be faced with the risk of loosing custody?
Before you answer yes, I ask you to refer back to that case a year to two ago where a teenager (16 or 17 I believe) refused to go undergo chemo for cancer treatment. It was unsuccessful the first time and the treatment almost killed him. However, because he refused, the parents almost lost custody of him. It was dropped later on because of his age but what if he was 13 instead of 16? Would the court have ignored his wishes even if he displayed full cognizance and maturity about the possible outcome?
What a child suffered a malady in which there was a 40% chance of dying without treatment but the treatment had a 60% chance of leaving them a quadriplegic or a vegetable? Shouldn't it be up to the parents to have the first right to make that decision of the child was unable?
In addition, while it might be successfully argued that people should have a license to breed, there are still very good and successful parents out there. Parents that have only thier childrens best interests at heart.
The government is simply incapable of providing the care and guidance a child needs. In support of that arguement, I only need to point how many teens leave group or foster homes and end up pregnant or using drugs or generally falling behind the curve of society.