Why does the Roster of quality say it's locked?

The (locked) note on the Roster of quality is there because the Roster is a list of companies that Toolkit downloads from the StockCentral service each week, as opposed to a regular portfolio where you can add or remove stocks at will. This list gets updated automatically, usually on Monday mornings, with the current top rated companies in the StockCentral service.
While you can't add or remove companies from this list, you can always double-click on any of these companies, do a stock study, and save it to one of your personal portfolios for further study.