Doesn't make sense to me.
>earth has been warm, full of water, with an atmosphere, rich in minerals and organic materials.
>majority of life has required in abundance what earth has always supplied with liquid water and temperate climates being absolutely necessary for survival and reproduction.
>oh but its not probable Earth's environment had the conditions necessary for life to start, it must have come from somewhere else with extreme conditions.

It seems to put forward an idea that extremophiles are ultimately the precursor to life on earth as that is what's necessary to survive a trip through space, but if that's the case then why is most of life on earth not extremophiles still?

It's speculated that most where when earth itself was had an extreme climate but life seems to have evolved to be less extreme as earth became less extreme itself but that only begs the question if life did come from space it means whatever planet they came from must have been more hostile than earth ever was.

This is before you get into how life could end up on a rock that managed to achieve escape velocity of not only its host planet, but its star system too. Implies a cataclysmic event which isn't unusual but is itself an event that would likely obliterate all life