OK, there were a few things I was missing (including noticing the word
"free". Sorry.).

I'm not sure what the free libration period would be if you magicly
displaced the Moon by 1°, or 10°. Or how long it would take to damp
out - that's an important question from the standpoint of pumping up
the free libration to turn it into a free rotation (a libration of
greater than +/- 90°). I wonder how much of the current free libration
(slight as it is) is due to some past impact(s). After all, w have a
good record of all recent impacts on the Moon (photos), as well as
their size (crater size) and some idea of their age. It would seem the
thing that would be hard to reconstruct is the impact angle (not
preserved in the crater shape except for extremely glancing impacts).

--
Brian Davis