I can't remember anything specific regarding why that detail is there but my guess is its regarding how close those two screws are to the bottom of the stabilator. They are the most difficult to install and remove.
As someone else mentioned, brand new nutplates have a rather high prevailing torque.
That coupled with the close proximity to the bottom of the stabilator makes those screws even more difficult to install and remove.
Tapping the slightly will alleviate the initially high prevailing torque.