I don't believe safety is jepordised on a flight at the moment (it may be when the engineering changes have taken full effect). The only reason for this is that staff don't want it to be unsafe. I know in my job, while I detest QF management and everything they say and do, I still do my job to uphold safety standards. If this involves a delay well so be it.
From the f/a's perspective I can see where pax safety may be compromised especially in a medical situation with a fatigued f/a.