Any creature in the Astral Plane is a "disembodied mind". These creatures can enter an Outer Plane, either by pool or by floating island.The flaw in that logic is that PCs do not age on the Astral Plane, but they do age on the outer planes. Souls are not alive, and so don't age. It's not an astral plane thing with them.
At no point is there any "aging". The minds along with their virtual astral bodies can exist anywhere there eternally.