Perhaps they (TPTB) thought they might use him to get the wild stuff out into the public fringe in case disclosure was ever needed. In other words, he was used to soften up the public...to prepare the soil, so to speak.
Yeah, that occurred to me also. Easing the general public into the idea. I suspect some Hollywood scripts were treated the same way. Make it part of the popular culture to ease the eventual shock.
Why in the world would space aliens talk to our leaders? They are all criminal sociopaths. Not worth a wooden nickel, with possibly the exception of President Trump. Time will tell.