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.
We had a NSA whistle blower, we now need a NASA Whistle blower!!!!