What irks me about all this is that it remained a "secret" quite well guarded for so long (and he characterizes as a global phenomenon, so gigantic surface area for public scrutiny/whistle-blowing)[1], but then I remember the PRISM program/Snowden revelations and I don't know what to think. Perhaps it's also valid to consider that it might be a top secret US aircraft that he judged to be of alien origin and no one in the military tried to correct it, for obvious reasons.
[1] - “Retrievals of this kind are not limited to the United States. This is a global phenomenon, and yet a global solution continues to elude us.”
But it wasn't secret. The narrative has been out there for ages but covered in disinformation so you can't see it properly. The disinformation caused people to see it as ridiculous, as was intended, so they ignored previous government whistleblowers with the same story.
Yup. There was information about the NSA's Echelon program floating around for decades before Snowden. Check out the Public Disclosures section of this Wikipedia article:
Despite multiple whistleblowers dating back to 1972, no one took it seriously until the Snowden leaks confirmed it without any doubt. For forty years this information remained below the surface.
[1] - “Retrievals of this kind are not limited to the United States. This is a global phenomenon, and yet a global solution continues to elude us.”