No, that's not what the analogy at hand. The designers of a stealth plane are just that. The right analogy would be if the navy seals designed a secret weapon, someone infiltrated their ranks and exfiltrated the weapons plans. Navy seals are not immune to moles. No org is.

Your implication that this was due to lack of proper security hygeine is unfounded. Security hygeine reduces risk it does not eliminate it. Risk is proportional to threat and attack surface, for an org like the CIA they have not-so-small attack surface and the whole world as their threat, so reduction in risk by means of common security controls and hygeine will not reduce risk from the most persistent and resourceful attackers.analogy to your reasoning would be "Google has an army of devs and security pros, so Chrome should never have a remote code execution vuln" ,no, as much as they may have money and talent, modern software is too complex for those resources to eliminate all bugs. Perspective is important.