That letter is Splane and/or Morris. More likely the latter, as he served as a medic in the US army and thus likely views himself as some sort of expert on anything "medical".
Edit: There is a LOT of detail in that Reddit link - there is someone risking a $#!+-ton by leaking all those documents.
The Reddit author singles out Sanderson in his comments - I can also imagine him as the author / co-author of this policy.
Edit 2: The more I think about this, the more bizarre it seems. The letter clearly indicates that any JW who "administers" (as noted in the Reddit comments, there's a lot left undefined) a blood transfusion is "an accomplice in a wrong practice" and is "violat[ing] the Scriptures". Yet, they do NOT say that doing so is a DF offense. So, it's "wrong" but not a "serious sin"? As noted in the Reddit comments, they refuse to put this in writing outside of the HLC context, so virtually no elders other than LDC members would ever even know about it, much less know if a JW nurse or doctor did so.
I don't get it. What's the point of laying down an uncommunicated, unenforceable regulation that carries no outlined consequences for breaking it?