Currently, turrets mounted on turret rotation lock blocks cannot be set to autofire.
If this is intentional behavior, there is a scenario in which I would love to be able to have autofiring locked turrets: Rocket launchers with seeker rockets.
By positioning rotation-locked rocket turrets on the hull facing perpendicular to the ship's direction of travel, seeker rockets can be launched at a target anywhere, and the turrets will fire regardless of the ship position.
This video (5s) shows what I mean:
This can still be done with manual fire, but auto turrets in this scenario would be great.