His dad is the donor, because the conditions of his surgery (bloodless) prevent his eligibility to receive a liver from the database of donors. His dad and he might die on the table or afterward. Family doesn't look so normal when they place two lives in the balance over the blood issue and say "Well, there's always the resurrection."
So instead of facing the possibility of one family member dying because of not accepting blood, this family faces the possibility of losing two members...
The father was willing to maybe die to possibly save his son? Why couldn't the son have been willing to save his father from having to offer his life by just accepting the blood? If he died, then his father would still be alive to support the family. If he lived, then he could be repentant.
You're right, it has to make this family look like brainwashed cult members if they're willing to let two family members die instead of one.
If the WTS ever makes refusing/accepting whole blood transfusions a conscience matter, there are going to be lawsuits galore.