I don’t see why the government would have such an interest in airbryushing out such exciting news.....
Oh wait, CONTROL is why...
IF we found out that an ancient race of humans ventured off this planet and is currently living in say the asteroid belt, how would we respond as an american people?
I think it would encourage us to spread out into the solar system and would weaken the power of the central authority, which is something the government would not like at all.
We would also want to meet them on equal footing if they were currently living in our solar system and if we did and a group formed an alliance with them this would also weaken the central control the central planner have over us.
That is probably why they would insist on airbrushing the past so to speak, so that it is like the pictures that the KGB has airbrushed....
It is my understanding that the airbrushing began long before NASA could have known the origins of the objects. It is unlikely therefore that they knew a distant past civilization was the source. HOWEVER, after years of exploration, being done at very different levels of technological capabilities (little robots rolling around on MArs, positioned purposely to avoid discovering ‘dangerous things’), I have no doubt that NASA knows much much more and is applying data collected in their explorations.