So it is your position that the 406.4(D)(1) language makes the existing "grounding means" into an EGC? I strongly disagree, for the reasons outlined previously.
BTW, since you see the existing grounding means as an EGC, do you have any problem with extending that branch circuit to a new outlet, using a wiring method with an EGC listed under 250.118? If that is not allowed, how do you make the distinction?
Your error, as I see it, is to assume, before you get to 406.4(D)(1), is that there is no existing grounding means. But I have shown you the
Code that establishes the armor of armored cable as (in the 1918 NEC) a
ground conductor and that is passed on through time as the language of the
Code evolves. The 406.4(D)(1) required grounding-type receptacle is connected to the grounding means as an EGC.
BTW,
let's keep it simple and stay with receptacle replacement, the question as the OP asked.