The thing about blood transfusions is; If it is against God's law, so what?
Has the ground opened up and swallowed anyone who took blood? Has anyone been struck by lightning or gotten leprosy for taking blood? I don't think so.
People receive blood and they live their life and then die normally, and the belief is that they won't get a resurrection. No big deal.
Refusing blood and the person dies and they have a hope for the resurrection; but it hasn't happened yet. So put one's in today, not the unknown future.