If character creation on a server is locked for any reason, then there is nothing a player can do to over ride that. CS can also not over ride that. The decision to open up the server again to new char creations is up to the WoW Devs and server engineers. They will do so when and if they feel it is stable and a good decision for the health of the game.
Unfortunately, there is never an estimated time when, or if, the char creation conditions may change. They may be going in blocks right now. As in, freeing up some spots randomly until they fill up again. Your friend can keep trying if they want and hope they happen to hit an open block of time.
There is a thread about it with players discussing it here . This comment seems helpful