Sorry this is going on oompa...
To the best of my knowledge, they consider you DA'ed if you accept a blood transfusion. If you're unconscious, they may not because you had no say, however if they really want to stick it to you they might point out that you should have had your medical directive on you and this should have been in your medical records for your doctor to know. They may argue you should have taken more precautions in order to prevent such a travesty.
However, if you chose to willingly accept a transfusion of one of the four main components (read: no-no blood), then as far as I know from what I have read, they consider you DA'ed.
I personally would just let it go. They did what they did, what does it matter WHY? They are a cult and have their own deluded reasons for their actions.
As for legal action, well, what's done is done. Even if they took back the DF'ing/DA'ing and announced it, you'd still be treated like a social pariah because of the simple fact that the elders "went there"...so you must have done something pretty heinous in the eyes of the congregation to warrant such punishment, even if it is recanted after it was doled out. Defamation of character is important, but not really a big deal unless it has affected your job, your home, or your livelihood. For instance, the things I was accused of by my ex, if they were ever reported to police for investigation, I would have lost all and any means of supporting myself that I am currently certified for even though I am completely 100% innocent. THAT would have been a defamation of character suit (and might still be considering my livelihood was threatened).
Like I said, personally I would just let it go.