I think I got my answer. Apparently the RHS decided that Juniperus xmedia was
too broad a basket. The cross of J. chinensis x sabina is now called J.
xpfitzeriana, which I assume just includes the Pfitzer juniper group.
'Shimpaku' is back to being a cultivar of J. chinensis, where it started
originally. Since many of these exotic cultivars have never been seen in the
wild, and some of them have never bloomed, like bamboo, their taxonomy is
anybody's guess.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"The trouble with people is not that they don't know but that they know so much
that ain't so."
Josh Billings (Henry Wheeler Shaw), 1818-1885

Iris Cohen schreef
I think I got my answer. Apparently the RHS decided that Juniperus xmedia
was too broad a basket. The cross of J. chinensis x sabina is now called J.
xpfitzeriana, which I assume just includes the Pfitzer juniper group.
'Shimpaku' is back to being a cultivar of J. chinensis, where it started
originally. Since many of these exotic cultivars have never been seen in the
wild, and some of them have never bloomed, like bamboo, their taxonomy is
anybody's guess.
Iris,

+ + +
I had hoped that this was what we had made clear (with the exception of the
part of the RHS), but I guess not.

The general feeling can indeed be described as "that Juniperus xmedia was
too broad a basket" or as I put it:
"everything that was once in the well-known
Juniperus x media ... [was either] ...
a mere cultivar of Juniperus chinensis
... [or] ... associated with 'Pfitzer' & al"

The part of the RHS is a little more modest than you make out. The entity
making the decision on conserving botanical names (including those of
hybrids such as Juniperus x media) is not the RHS, but in effect the
Permanent Committee for Nomenclature of Spermatophyta of the IAPT (the
formal responsibility lies a little higher up, but the Committee does the
actual work). In this case the RHS was consulted in an advisory capacity.

The RHS does make the decisions on CULTIVAR EPITHETS of conifers
PvR