To close the saga of the master rear brake cylinder replacement: The dealer asked the national warehouse to cannibalize from their assets; and the parts were expressed mailed and have been installed as of today. Problem solved.
Downside: this process took nearly a month. I know, I know, it would have been so simple if the dealer had just taken the parts from their existing inventory it would have been solved in a day.
I would hope that as the bike goes into another year of production (and apparently unchanged) that the spare parts supply chain will get better.