I don't know what Liberia has to do with it.

Weeding (deselection works) is a fundamental part of collections management. Every trained librarian is going to understand this.

The interlibrary loan system has mechanisms in place to make sure the member libraries keep two copies of each work in each region. Collection managers consult these databases during weeding to make sure they don't deaccession the last copy.

If the monograph was never collected by a library and it gets caught up in a destructive scanning project then I guess it was pretty "rare" in a literal sense. "Rare Book" in library land is sort of a term of art and I'm not sure if the books in these destructive scanning projects meet the criteria.