Finding this more persuasive having mulled this for a week. Eaton involved genuinely special, exigent circumstances—a vacancy created by sudden illness to a posting in Thailand, in an era before telephones or airplanes. theatlantic.com/ideas/archive/…
The circumstances in Eaton were such that the vacancy was unavoidable and the technology of the era meant it just wasn’t feasible to get a Senate-confirmed substitute in place halfway around the world in any reasonable amount of time.
Extending that ruling to cover what is essentially a deliberate hack of the appointments clause just doesn’t make a whole lot of sense. If that exception stretches to this case, the president can effectively circumvent confirmation whenever he likes, & the clause is toothless.
Also, it’s a lot more intuitive to say that an ‘inferior officer’ could fulfill some of the functions of the relatively modest post of vice-consul temporarily without thereby becoming a ‘principal officer’. Much less so for Attorney General given its sweeping responsibilities.
