ATR issued an AOM warning of operational and maintenance hazards whenever elevators become uncoupled - essentially avoid opposing inputs and check for structural damage after any elevator disconnection.
Well that's pretty obvious, isn't it, ozaub? The idea is the jammed side be left alone and the aeroplane controlled with the serviceable side, not have the pilots fighting each other with their prongs. Instead of casting doubts on the system, you'd be better off concentrating on the CRM that resulted in this fight. You do fly/have flown a type with split elevators, haven't you?