A little less name-calling here would be well-received.
I was always taught that in cases of
catastrophic failure, the cabin crew can initiate an evacuation.
Such situations include (
inter alia) ditching, forced landing and fire
in the cabin. It does not include a tailpipe fire.
Should the Purser/CSD/#1 suspect catastrophic failure, first action should be to contact the flight deck. The normal "three calls" rule would apply, I suggest. If the FD crew are a tad busy they can just say "Yeah - we're handling it - standby".
The cabin crew should
only initiate an evacuation in such cases if they have reasonable cause to suspect that all up front are incapacitated.
In case of a problem, it is thoroughly dangerous for everybody to start taking action and making decisions affecting the lives of a couple of hundred pax without maintaining the best standard possible of CRM - and that means
communicating. Such communication appears from what I've seen to have been sadly lacking in the reported case. However, I accept that the full story will not have been told yet.