It sounds like there is alot of uncertainty involved in lunar minerals and I would appreciate you lending your expertise to discussing the above referenced article since it is an update to prior work.

The Moon’s synchronous rotation was established very early, but exactly when is not clear. It most likely occurred after the Moon had completely solidified.

Ok, And lunar crust refers to latter. A stratification of rock due to cooling of the Moon.
And I suppose, the assumption or default position until proven otherwise, is the Moon formed from a collision with proto-earth. and that it was closer to Earth and began as molten ball which cooled and might have re-heated from large impactors near the point of time the Moon as molten ball was solidifying, and as solidification continued the latter larger impactors may only partially re-melted large regions [rather than approaching a global effect].

And it seems at point of enough surface had cooled so as not having partial re-melting
via large impactors one dealing with time of lunar crust formation.
Was Moon tidally locked before the lunar crust formed?

About 1000 km — that is the estimate of the current thickness of the lunar “lithosphere” (i.e., the rigid, cool outer layer of the Moon.) On both Earth and Moon lithosphere/asthenosphere is not the same as crust/mantle. The former is a mechanical boundary, based on material strength while the latter is a chemical/mineralogical boundary, based on composition.

So it seems to me, if on earth, if one somehow remove section of earth crust, you would exposing hot interior rock. Or if one drills 5 km under the surface one will have fairly warm rock.
So, if want “geothermal energy” on the Moon, how far would you need to drill. Is there anywhere on the Moon where it be is would less than 5 km?
And there seems limit to how far one drill on Earth, we have not reached it, but anything more than 20 km might nearer it, whereas it doesn’t seem that one reaches same limit at 100 km deep.

Or perhaps one say it this way, present conditions on Earth defines earth’s crust and mantle, whereas it seem with Moon it may be referring to a distant time in the past [a billion plus years ago]. And if this is true, the crust/mantle of Moon could dependent on time. So 1 billion years ago to present you have crust which was different than crust 2+ billion years ago.

It seems I remember reading about how the Moon has fractured crust. And seems to me that at some deep it stops being fractured and at such point it could be boundary of lunar layer.