Fair call Barkingmad.
I have just read the report the OP mentions. It is definitely something that is worthy of a Bulletin in my mind but technically Boeing don't have to bring it to the attention of the airlines because of the low rate of occurrence as mentioned earlier.
There seem to be two possibilities for causing the rate jam,
1/ an internal foreign object
2/ an external foreign object
Is the external case something that could be addressed during walk-around or would an external foreign object be so minuscule that there is no benefit in checking?
This from the report:
The second cause of a rate jam is debris, such as ice or stones, becoming lodged in the external linkage that operates the steering valve. A jam of the external summing linkage that operates the input lever to the steering valve will have the same effect (rate jam) as a jam of the valve’s internal slide/sleeve. The steering assembly is shielded by a plastic cover, 35 but is not sealed and is exposed to environmental conditions while the aircraft is on the ground, when the gear is extended on approach for landing, and until the gear is retracted after take-off. No testing or research has been conducted by Boeing to attempt to replicate a rate jam scenario due to an external linkage jam.