The nub of the matter; it is about crews having a CSM on board that has to work. In all the threads, on all the pprune forums, there is no one that has declared a case for CSM's not doing cabin service duties (with any reasonable argument)... Speaks volumes?
Bassa's gripe? we didn't suggest/agree it; BA imposed it.
Of course this has then led into, we strike because we have lost a,b,c and probably d (New/mixed/start again Ba fleet) when it is introduced.