Yes, Apples can be grown in the Southern California
region with some success for the home gardener.
We had relatives that lived in Apple Valley for many
years and they did grow some tasty (tree ripened,
allowed to become mature on the tree rather than
picked a little too early for fresh shipping like most
commercial Apples are) Apples there.
Several rootstocks for Apples are grown from seed,
not simply rooted cuttings grown on and later used
for budding and grafting. Most store bought West
Coast and Pacific Northwest Apples were propagated
at some point in time, in more recent years, onto an
EMLA type (dwarfing) rootstock.
If you want a Honey Crisp Apple tree to grow on for
Southern California it may be prudent to buy one from
a growing nursery that specializes in growing Fruit
Trees for the commercial growers as well as for the
homeowners, rather than taking seed from a store
bought fruit, germinating them on and hoping to find
one seedling tree out of several trees that may be
close but not the same as the Honey Crisp. Although
I think I recall that the Gordon Apple came about
as a chance seedling from the Southern California
region.
This link below from a well known and reliable source
nursery may be more insightful.
DWN: Garden Compass: An Old Rose: The Apple:
Jim