"Pilot William Graham, 65, told authorities that his airplane, a Cirrus
SR22, stalled at 16,000 feet, ..."

I'd rather say that it was the pilot who stalled the plane.

"... then encountered turbulent weather at 13,000 to 15,000 feet that
sent it into a spin, according to the Stockton Record newspaper. Graham
deployed an emergency parachute ..."

A spin at 15'000 ft is a non-event and can easily be recovered without a
chute.

So my bottom line is: The pilot should contact a good flight instructor.
(This doesn't change the fact that the chute saved two lives.)

Stefan