The folks who approved the RFM don't write (or approve) the MEL... The MEL is an operational approval, and not a certification requirement. The RFM and MEL should be consistent, but I suppose that's only in a perfect world.
That's true insofar as the MEL is written by the operator, but it is based on the Master MEL (MMEL) which is written by the manufacturer. The MMEL will be written by a group of people that includes the same 'folks' who write the RFM.
In this particular example, the restrictions on flight with a degraded AFCS system will be listed in the RFM Limitations section, but the MMEL will set the time limits before repair (as well as the restrictions.) The main point, as I and others have said, is that the same defect should not be continuously re-defered! That is most certainly against the spirit and intent of the MEL process and points to a poor safety culture.