JC, I think what the JAA are proposing is already common practice among most airlines, certainly in Europe and the US. In fact, the mid-air between the DHL and Siberian over Switzerland was caused (in the last instance) by the Siberian aircraft acting against his RA, while the DHL followed his.
Pilots already say "TCAS Climb / Descent" to ATC when following an RA; this should stop ATC from issuing further (vertical) avoiding action.