Here it appears that the 1830 typesetter accidentally replaced the singular abomination with the plural. Although the plural abominations is considerably more frequent in the Book of Mormon text, there are specific cases of singular usage that contextually do not permit the plural usage:
Note, in particular, the pronominal use of the singular it in the last two examples.
There are no other examples of doing(s) occurring with abomination(s), so a comparison with another example of this specific construction “doing(s) of abomination(s)” is not possible. The critical text will maintain the reading of the earliest textual source here in 2 Nephi 25:2.
Summary: Restore in 2 Nephi 25:2 the singular abomination, the reading in the printer’s manuscript (“doings of abomination”); the singular is clearly possible in this context.