I have never been a “subject”.
Neither of my parents were “subjects” to England or any other nation.
Blackstone was an English Jurist & Judge. Yes, he was an authority on English Law. Not US law, and they are not the same.
This is not as simple as you suggest. And I do not have the time today to find you the reference material to support what I said.
Read the other quotes in the article, and then go to the record yourself. The Founders used British law as the basis for much of our law. It makes sense. It’s the law they had and knew.