You get involved. You go to seminars, study up on blood, the history of transfusion medicine, medical ethics, legal cases and the like if you're motivated like I was. Then it hits you that there is no biblical basis for distinguishing minor blood fractions, that DF'ing someone on these grounds are without biblical support and that you're ashamed of the whole thing because the supposed principle of showing respect for life is actually violated by the prohibition. I'm reminded of Jesus "breaking" sabbath laws to heal people and how disgusted he was with the pharisees that they couldn't see that what they were doing was hypocritical and violated the very laws they claimed to support.
It took me 8 more years to walk away after I knew that.
This organization is a real piece of work. It takes some of the best people and inverts their goodness into badness without their even being aware of it.