Strong disagree. The person in question probably thought it was a private repo on Github and had a massive deer in headlights reaction when they got contacted. Whoever this is, lost their job, possibly security clearance and more. This was 100% life altering "mistake"/gross incompetence decision they made.
That doesn't support the theory that it was a mistake. That was intentional action. Maybe he was being blackmailed, and was coerced to do it. Or maybe he was a foreign agent or sympathizer who had infiltrated the organization.
I've been a government contractor before, it does not employ best and brightest, it employs the average and below generally.
For some people, yeah, this could be a career killer. For some other people, it might just precipitate a flight back to Moscow or Beijing or something.