It would be easy to hide it within another public project that plausibly would need those researchers and experts. Announce a mission to build a moon base, or put humans on Mars. Part of that will need advanced robotics and AI, so now you have a Black Budget project hidden within a public project, and a perfect cover story. Plant 42 has been cranking out Black Budget surprises for decades, though they don't need a cover story, everyone knows it is a "secret" aerospace R&D and manufacturing facility.
It would be easy to hide it within another public project that plausibly would need those researchers and experts. Announce a mission to build a moon base, or put humans on Mars. Part of that will need advanced robotics and AI, so now you have a Black Budget project hidden within a public project, and a perfect cover story. Plant 42 has been cranking out Black Budget surprises for decades, though they don't need a cover story, everyone knows it is a "secret" aerospace R&D and manufacturing facility.