Ben There:
Setting 90% N1, on the A320, will assure a safe airspeed (assuming you're not approaching a stall)
An even better strategy, is to select 80% and a degree or two of attitude below normal cruise.
What you want to do is get out of coffin corner, especially if things are getting turbulent, and by setting a lower thrust and attitude you will do just that.
Manaada:
I don't fly Airbus, but I find it a bit strange that an aircraft with so many protections built in, will allow the autotrim to trim the stab into a position that you simply can't fly out of.
So will the Boeing, as was amply demonstrated on an approach into a European base a few years back, when the pitch got out of control.
Unfortunately, there are still some corners of the envelope that will always remain outside controllability. You want a trimmer, but that trimmer can also reduce elevator authority (as it can on the Boeing). You want lots of thrust, but that thrust can reduce elevator authority (as it can on the Boeing). You want rudders, but that yaw can diminish roll control (as it can on the Boeing).
With an aircraft, both in design and in flight, you are juggling any number of interconnected and competing controls and parameters - any or all of which can be present at the same time. And from that melee of actions and reactions you need to create stable flight, which is not always possible at the far edges of the envelope. So the idea is (and always has been) to remain within the established safe envelope, where all of those many competing aeronautical parameters can coexist and operate in safe harmony.
The problem lately, is too many aircraft exploring the edges of the envelope where they should not even dream of going. So rather than fiddling with the edges - changing this law or that law - we need to concentrate more on not letting aircraft get to the edges and corners of the envelope where they have absolutely no business being.
One minor mitigation would be to take fuel restrictions off pilots, so they are not flying in the higher corners (and adjust the pax figures to compensate). But no company will do that....