It's promotion that one is, and should be, held accountable for.
Oathing someone just says 'This guy has dedicated his life to learning more about the glorious Empire.'
There are people who insist on only oathing people who would otherwise be in their sect, but this is a misnomer, anyone can give anyone else the Blood oath. If you're not doing something more important right that second, it's your responsibility to the Empire to oath as many people as you can.
However promoting them is not an obligation until someone tells you it is.
If you heard that phrase it's only because you heard (or it was meant) 'promoted' instead of oathed.