Can you elaborate there? This seems like a very speculative statement to conclude 'completely unlikely'.

Geological-timescale variability is VERY conducive to evolution.

We also don't have timescales for abiogenesis in a sterile environment - i.e. given the right ingredients and energy input, no existing life forms...how long does life take to appear? There's no particular reason that timescale has to be very long - and we know life on earth got started pretty damn quick after the planet cooled off enough (EDIT: in the sense that the planet is ~4 billion years old, the earliest life is dated to 3.5 billion years old, so the number is somewhere between a little over 0 and 500 million years).

> Over geological time period, the zone is likely to suffer unpredictable and novel variability

Earth does that too, though. Ice ages, the odd large impact, etc.

I meant far more frequently than on Earth, and far more extreme.

"Life finds a way" - but if the temperature suddenly jumps 100 degrees because your goldilocks zone librated into the sun, then you ain't got much capacity to evolve protection from that.