It sure is. Logically, by his definition there can only be one world-class goalkeeper at any given time.
Just saw this - you can have 20+ players on a squad, you know
But my definition is simple - a world class player (or manager, or anything) is one who every single team would like on their books as a starting player. So, Emre Can isn't world class, for example, because there are a lot of teams who wouldn't have any use for his limitations. Lionel Messi, peak Suarez, both Ronaldos, Figo, Xabi Alonso, DeGea, Becker, Wambach, Ancelotti, Guardiola, etc. - these are all players and managers who every single team would look at and go "yeah we would love to have them here"
That's my definition of "World Class"