I don't think that's an accurate statement of his position. In fact, for Archbishop Lefebvre, the Latin Mass was not even his biggest issue. He actually cared more about some other aspects of Vatican II such as religious liberty and ecumenism. The article that got him suspended by Pope Paul VI was titled "Do we have to become protestants in order to stay in the Catholic Church?" He pointed to "Dignitatis Humanae" and other documents of Vatican II as equally destructive of the faith along with the New Mass. And there aren't thousands of Vatican II documents, only about a dozen.(I went and counted to be sure, and there are 7 major documents and 9 decrees.)
It was the vagueness that made it dangerous and only because the infection was so deep and prominent.
Vagueness in a magisterial document is a capital offense. It's just as bad as , or sometimes even worse than outright heresy.
"Vagueness in a magisterial document is a capital offense."
Bingo! - Will we see this as your tagline?