To be fair, you are certainly correct about the freezing part.
However, GP's other points remain valid. Not much survives the heat of an impact, even less (molten) debris ejected into space. Simple organic molecules are destroyed easily with heat (and radiation), not even talking about (primitive) life forms.
As for the article, we can safely assume that probability of life originating from Mars is about the same as amino acids from "outer space" hitting the earth - or the remains of FSM's tomato sauce.
In other words, pure fantasy.