I was also disappointed. "Rebuilding" to me does not mean "restore from a file I copied earlier". In fact, thinking about it more, it would seem in this case that you had two backups, one on disk locally and one on tape. This is a great idea for disaster recover situations but had the restore from tape worked this whole secondary method would not be needed. In either case, tape or disk, we have not rebuilt the master database, we have restored it from backup.
I am happy to be corrected but I find the title of this article very misleading.