The general philosophy of classified information is that it's revealed on a need-to-know basis. Except for a few crude simplifications at the lowest level, the

The general philosophy of classified information is that it's revealed on a need-to-know basis. Except for a few crude simplifications at the lowest level, there is no fixed heirarchy where you've just given all the info you want below some level. The folks at SpaceX, including Musk, probably got exactly the minimal amount of classified info they needed to safely launch the thing into orbit, e.g., the orbital parameters, its weight and exterior features, its robustness to vibrations and the like, the electronic interface for monitoring its health, etc.