Redundant command as an affirmation of authority?

Alice is being officious.

Assertive of authority in an annoyingly domineering way, especially with regard to petty or trivial matters.

Lexico

In an attempt to reiterate her authority, or just to show who's the boss, Alice ended up beating a dead horse when she asked Bob to stop making noise with his tools (which he stopped using an hour earlier).

Wiktionary:

Verb beat a dead horse

(idiomatic) To persist or continue far beyond any purpose, interest or reason.

After having shown us three hours of instructional and safety videos, the inspector was simply beating a dead horse by telling us to buckle up as we got into the van.

Alternative forms: flog a dead horse