Well, it obviously was, and the Bishops obviously "signed off" on agreeing that it should be, as I'm sure that the "Novus Ordo" went through all the relevant review procedures.
Church historians will eventually detail just exactly what "review procedures", or lack thereof the Novus Ordo went through. The story of how it was concocted and implemented does and will make fascinating reading.
However, to return to my basic point. This was not mandated by Vatican II.
The documents of this council nowhere support the assertion that Latin is no longer to be the liturgical language of the Church.