...is that life forms a kind of amplification process.
If you have some random soup of molecules formed by abiotic processes then apart from some small biases brought about by parity-violating fundamental physics we expect complete symmetry between left- and right-handed molecules.
But life, arguably, forms a kind of amplification process. Competition between molecules with different chirality might serve to increase any initial small difference between one group and another. So what starts as almost exact symmetry results in a planetwide bias one way or the other.
But there are two issues.
(1) Could such a planetwide bias show up strongly enough in the polarisation of light reflected from the planet. It seems very unlikely given how messy a planet is. Let's say you pick a million different types of molecule than come in chiral pairs and for each molecule pick one of the pair, discarding the other. Now jumble up many different copies of each of these molecule types. Your chances of detecting chirality from afar is minimal even though, in some sense, the mixture is perfectly chiral, because of the overall randomness of the mixture.
(2) Could any other physical processes cause such amplification? The answer is yes. For example some kinds of crystal growth can result in homochirality.
So I'm pretty sceptical despite the idea being neat.