SQL Server Service Broker and Deadlocks
When the service broker pulls messages from the queue using an activation stored procedure (or in any method) all the normal locking rules apply to the queue and the objects which are referenced in the code after the receiving of messages from the service broker queue.

Note that the information in BOL that you quoted is only true is you do the receive within an explicitly defined transaction.  If you receive a message and there is no explicit transaction to rollback then the database can't put the message back in the queue.