The question in the title and the body are different. There are no tidally locked objects in the Oort cloud. The sun's tidal forces at that distance are not sufficient to lock an object's rotation. Tidal locking doesn't mean 'co-incidentally' having the same rate of rotation.
Tidal forces decrease with the cube of distance; tidal torques decrease with the sixth power of distance, so are much less significant relative to gravity, which decreases with the square of distance, in the Oort cloud. Moreover, the time for tidal lock to occur increases with the sixth power of the distance. Tidal lock also affects large objects more than small ones (in general) and most Oort cloud object are small.
There are other things that can cause changes in rotation rates: gravitational interactions in close passes with other objects, small impacts, the YORP effect. All of these are rare or weak in the Oort cloud, but stronger than tidal locking, and so would tend to cause any object which by chance had a synchronous rotation rate to break that co-incidence.