Glad to know the circuit works in practice, not just in simulation.
If you want to protect against failure then you can add an SCR overvoltage crowbar circuit to the output such as
this, which is commonly used in power supplies for that purpose.
That circuit turns on the SCR to clamp (short) the output to ground if the voltage goes higher than about (Vz + 0.7V) where Vz is the Zener voltage.
The circuit is reset when power is removed.
Of course, since the output is now shorted to ground, you need something to disconnect the circuit to avoid frying something else, such as the fuse shown in series with the input of the regulator.