I had a conversation with someone I know on the local HLC a few years ago. His remarks go along the same line in terms of what to do with minors. He told me that there's basically no chance of winning when it comes to refusing blood for minors and the society is simply not interested in getting involved to the degree they once were (his words summarizing the stance). He told me that they will recommend to parents to tell the drs they don't consent to such treatment but won't contest.
I've also see a consent form similar but along the lines of "we do not wish for our child to have a BT but recognize that the hospital/physician may do so if there is a medical emergency". I don't have a copy of what I saw but remember thinking it must have been drafted in conjunction with WT legal.