It changes every now and then, some worlds go back to available/limited and otherwise.
It seems their system already includes our default server in the numbers accounted.

Say, Ridill (Selbina) is shown as limited, with 10 spots left for example, and on the other hand you have Masamune (Wutai + Gysahl) shown as closed.
If 10 people from Wutai (=Masamune) move to Ridill, Masamune will be shown as limited again.

So yeah, this is going to be... fun moving a whole LS on another server.