Thats an interesting way to do it.
At my company, when it comes to shutting down an engine, or switching off a generator, or anything else that significantly effects the operation of the aircraft and can be confused with another switch, both pilots participate in the QRH.
For example, let's say you get a left engine fire indication. The pilot flying assumes control of the radio and asks for the "Immediate Action Items" for a left engine fire. The non-flying pilot then pulls out the QRH and starts reading the procedure (all QRH, and any checklist, procedures must be read aloud for CVR confirmation).
The non-flying pilot will read "Left engine thrust lever - confirm and idle" and place his hand on the left thrust lever and keep it there without doing or saying anything. The pilot flying will then look at the EICAS once again to confirm that it is indeed the LEFT engine that is on fire, then look at the non-flying pilot's hand to make sure it is indeed on the LEFT thrust lever. If it is, the pilot flying will say "Left engine thrust lever confirmed, idle." At that point, the non-flying pilot moves the thrust lever to idle and both pilots monitor the aircraft to make sure the bad engine is indeed the one that has been commanded to idle.
This banter back and forth between the pilots then continues on to shut the engine off, turn the fuel pump off, push the fire push button, and discharge the fire bottles. It is all done very slowly and deliberately to make sure no mistakes are made.
That's just the way my company does it. Many other airlines use a very similar approach to it, apparently NWA doesn't.