"The names of cultivars that have won the AHS Stout Medal may not be used with any prefix or suffix
to create a new name subsequent to the cultivar having won the award."
This rule to me definitely implies that if other than Stout Medal winners prefixes and suffixes could be added to create new names.
Also the specific mentioning of garden names and possessives as prefixes that might not be allowed implies that other prefixes might be allowed. I saw no rule specifically saying no prefixes for any plants would not be allowed to create new names when added to an already existing name, but that they are all reviewed and that is preferred not to use an already existing name.
