It did leak. Everybody "knows" the government has been experimenting on Aliens and alien technology since at least Roswell. There are even articles in the New York Times about warehouses storing alien artifacts!
That is a good point. If you were in possession of world-changing, society-breaking, panic-inducing information, how else would you prepare society for eventually hearing the full truth?
You would do it as a laughable joke over a long period of time.
You would do it as a laughable joke over a long period of time.