It's actually just that the sample is using a tpk (.tpk file, tile package on disk) as a basemap. The tpk has only the first few top levels of tiles so as to not take up too much space on disk, and so the map won't let you zoom into beyond the largest scale level. Replace the ArcGISLocalTiledLayer in the sample with an ArcGISTiledMapServiceLayer for example, and you should no longer see these scale constraints.
~elise