I have read the Get Started guide provided by RabbitMQ and have even contributed the sixth example to stormed-amqp, so I have an inkling of knowledge about AMQP.
However
In a multitenancy system you would make queues secure by defining the permissions that users have. Read the access control section of the RabbitMQ admin guide here http://www.rabbitmq.com/admin-guide.html
Start by making everything happen inside vhosts and block the generic vhost entirely, i.e. don't let anyone declare queues and exchanges on vhost "/".