Hi! Once again, we're only talking about Prometheus' portrayal. Advent is irrelevant.
Prometheus never once established the dust will return to a liquid form if unsuccessful in finding a host.
It also doesn't show the goo re-atomise when exposed to atmosphere in the structure or on the ship. In fact, Prometheus only shows atomisation in contact with a host, not atmosphere, and only once.
And it certainly never establishes that the 2000 year timeline interfered with a process it never actually establishes.
All of these explanations come from external sources or inferring information the film does not at all provide.