Those are some good questions. I'm actually not sure if there are any Zoysia sod farms in SD. I know that mostly San Diego deals with St Augustine, Fescue, and a few others. I hope there's at least some place around here that does Zoysia. As far as Zoysia turning brown or yellow in winter, unless we have a very cold winter, you shouldn't have to worry at all. I put the official specifications into the article just to be on the safe side. I've never seen a golf course in SD with yellow and brown grass, and a lot of them use Zoysia around here I'm told.
If I were you, I'd first see if there are any local Zoysia sod dealers in SD. If there are, I'd call them and ask about their particular breed, since there are multiple types of Zoysia. I would think that there is at least one breed of Zoysia that's perfect for San Diego weather.