Do you think there is a case, however weak it may be, for forbidding blood transfusions?
No. It’s a gross misinterpretation of the kind the Jehovah’s Witnesses specialize in. The Council of Jerusalem appears to have desired us to not eat the blood of animals, but that goes back to the Noachide Laws, and it is not a sin worthy of the draconian punishments that J/Ws inflict on members who receive blood transfusions, who they effectively anathematize for life with no hope of repentance.
The J/Ws are an evil cult, and a predatory one; their members are the poorest in the US on a per capita basis (conversely, another cult which historically also rejected the identity of Jesus Christ as God Incarnate, the Unitarian Universalists, but which now mostly just reject Jesus Christ altogether in favor of a religion that as far as I can tell is centered around far-left political agitation, are the wealthiest, probably because of their membership consisting heavily of land owning descendants of Yankee settlers in Boston and New England, “Old Money” as they are known, the aristocracy, and also wealthy left wing intellectual converts and fellow travelers. John Adams and Frank Lloyd Wright are prominent followers; prominent heresiarchs include Ralph Waldo Emmerson. But at least the Unitarians in all of their snobbery do not prey upon the most vulnerable members of society in the way that the J/Ws do.
You are quite correct in a willingess to receive blood. Also, if possible, give blood donations. In the US, this is also a way for the uninsured who are not poor enough to qualify for free state healthcare via the MedicAid programs such as Medi-Cal in California, or senior citizens who get Medicare, which covers nearly everything (major exceptions include optometry and dentistry, since apparently seniors don’t need to see or chew their food), is to donate blood. I am planning on a blood donation at some point this month. I am blessed with very accessible veins in both of my arms and have never had anyone have difficulty giving me an IV; this, my lungs, and my skin and eyesight and hearing are practically the only systems on my body which are functioning well at present (prayers for my health are appreciated as practically everything else is malfunctioning).