Using the feature should per restricted by a user right: I think for now we can start by requiring "pagetranslation".
Currently I can see http://pagemigration.wmflabs.org/wiki/Special:PageMigration as unregistered user. On Wikimedia wikis it can be restricted to translation admins for now, while on the test wiki you can give "pagetranslation" to all registered users.
Version: master
Severity: normal
URL: http://pagemigration.wmflabs.org/wiki/Special:PageMigration