Aaron,
Yes, peculation reigns!
But to say:
"Stating that A. m. can't possible have genetic resistance to V.d.
because
the former was never exposed to the later is a faulty assertion."
Following with:
"It could possible be that whatever the gene combination that expresses
SMR was there to help A.m. combat something in it's natural
environment.  It could be any number of things.  Whatever is the reason
we probably will never know."

- is is definite -yes or no, and could is possible!
I suggest that ability to protect against V.j.(d.) or any other attack
on the bee is unlikely to be result of a previous experience from some
event that has nothing to do with V.j.(d.) or at least a circumstance
where similar molecules of protection are involved. The latter part of
the sentence being important.
It is possible that bees have come across pressure from other species
with similar or identical molecules to those that aid V.j.(d.) in its
predation on A.m. and these are "residual" in the present A.m gene
pattern. These traits may then may be selected for in "our" battle
against circumstances that harm our bee colonies.
Or, as suggested, it is a trait that was gained from an earlier type of
bee.

Agreed, chance is always there, and the gene code has to start somewhere
- but surely the greater percentage on traits are due to environmental
pressure, with the result that traits are due to exposure to a problem!
I am not disagreeing with the possible presence of SMR in A.m. - but
what I am trying to stress is where does this come from!
There is most probably no direct answer to this question, but it allows
for speculation due to its existence that it came from an earlier bee
type which has conferred other genetic traits on to its offspring that
may give us an insight into other latent traits that might not be
apparent but useful.
Hence the strong argument for in depth study of other bee types and
their protection. Also, it lends itself to the idea that there is a base
to the idea of G.M.

Peter - thinking being devil's advocate can lead to tight corners!