I find it harder to believe this part of the story:
In addition to burial sites, there’s another top secret facility at Groom Lake for mothballed projects. Known as Dyson’s Dock, it is said to be housed in the lower bay of Hangar 18 and may be a sort of classified museum, where base workers can view retired aircraft that have not been publicly unveiled.
If old projects are buried, presumably for security, why are some on display for those who are sworn to keep quiet?
It seems, if they exist, that they would more likely not be retired projects but ones in extended storage with the presumption that they still have some usefulness.