Whilst I believe that the reaction of the Government and therefore the regulator is OTT, knee jerk, and any other critical adjective that one can imagine, I don't for one minute believe the intent is that the "safety FA" is there to determine and thus intercede if a lone pilot attempts something sinister.
I suspect the rationale is twofold. If a safety FA is present, then a lone pilot is probably less likely to attempt some thing sinister but more importantly, s/he can open the flight deck door and allow the other pilot in.
Another "we're keeping you safe action" from a federal government near you!
