The docblock for commerce_order_statuses() says:
* Returns an array of some or all of the order statuses keyed by name.
* Order statuses can only be defined by modules but may have settings
* overridden that are stored in the database (weight and status). When this
* function is first called, it will load all the statuses as defined by
* hook_commerce_order_status_info() and update them based on the data in the
* database. The final array will be cached for subsequent calls.
I can't see anywhere in this function where the database is hit. The only function calls are to invoke the hook and then drupal_alter().