I see your reasoning though don't agree with it.
You are looking at what was written nearly 2000 years ago in reference to scripture nearly 1500 years before that and trying to apply it to a scenario that was not envisaged at the time. The first successful blood transfusions didn't happen until the 19th century. Acts was probably written late in the first century.
That's not a good argument as we can say the converse is true. How many times has man believed he was following God's wisdom whereas in reality he was following his own vain imagings?
It comes back to how we understand the sacred writings of our religion. The JWs are the only Christian denomination that I'm aware of that interprets the bible in a manner that extends to blood transfusions. I don't agree with it, but respect their right to have their beliefs.
I'm not sure you understand what I am saying.
I'm going to assume you know the difference between a law and a principle. Hopefully I assume right.
Just in case...
Law - Do not consume alcohol.
Principle - Consuming alcohol will kill you.
Which is greater, law or principle.
Principle right? It is a fundamental truth.
So knowing the principle, you don't need the law. Agreed?
Another one...
Law - Don't commit adultery.
Principle - One who looks lustfully at a woman commits adultery.
Say the principle was given ten million years ago.
Does it change? No. It's a foundation - it never moves.
Ten million years into the future, after the principle is given, (just for argument sake) a new therapy which allow for absorbing alcohol into the body through the pores is introduced into the world. Pornography is introduce into the world.
Do you need a law stating, "Do not watch pornography?"
Do you need a law saying, "Do not use this therapy?
I did highlight the principle concerning blood.
Do you need a law stating, "Do not take blood through your veins?
Here is another one...
If the Bible prohibits eating blood, am I allowed to drink it, since there is no law stating, "Do not drink blood?"
There is a big difference between eating and drinking.