The query has to return a pages collection, not a boolean value. Also, in a pages field you will have to actively select a page (or set the value programmatically, as mentioned), from the queried list. So allowed values should be all children of the artists page, from which you then select the one that corresponds to the current user.
Another approach to limit access to pages would be via a page model, i.e. limit access via the isReadable() method, see Author acces to only the pages they've created - #2 by texnixe