You are confusing secret+ classification with CUI.
Above I specifically refer to SCI, the designation for things of dire national security impact, which quite literally mandates that information be fully compartmentalized and unattainable to the public. Above that we have SAPs or special clearances (e.g. Q for Nuclear, YW for White House).
It is not possible to work with nuclear weapons, serious satellites, advanced drone weaponry, or similar without first getting an SCI clearance. In fact all of these are prime examples of their specific marking compartments. There are even regulations below this (e.g. ITAR) that control who gets to work on military technology in general.
there is a doctrine of born secret. and it is a contingency.
if i, or you, or anyone, was to independently realize how to increase yield of a weapon, or create a nuclear isomer weapon, it is secret upon conception.
knowledge is discoverable, and cant be stopped, only access to the tools of production can be stopped.
that is why you CANT stop motivated persons from making independent discovery, you have to prevent your adversary from knowing what you do/dont know, and what you are/are not doing.
