If flying into a cb is verboten, which of course it is, but to the point that a loss of aircraft is likely because of a flight control system that doesn't appreciate severe turbulence then several things need to happen:
The wx radar has to be on the MEL and a diversion required if it fails.
Pilot training has to be ensured on the make & model of wx radar.
If it really is critical and will cause a loss, there should be some type of wx radar redundancy, especially for long haul aircraft.