Why is the discovery of chiral molecules in space a big accomplishment?
The story is a big deal because it might help explain why molecules in living creatures have a single chirality

One of the great mysteries of living systems is that, when they use chiral molecules, they only use molecules of one chirality. There is no obvious mechanism to kick-start this preference and, while there are many esoteric theories, there is very little evidence that explains why one chirality was chosen over another.

Proteins are, for example, made from amino acids which are almost all chiral. And they are all left-handed (technically they are all levorotatory, see wikipedia). Most sugars used in biological systems are right-handed. There are simply no convincing theories that explain the origin of this preference.

One modern theory suggests that there is a subtle energetic preference for one chirality caused by the interaction of molecules with the electrons emitted in certain types of radioactive decay (the weak nuclear force involved in radioactive decay is one of the few fundamental forces to have a mirror-image preference). But other experts think the preference is arbitrary.

Resolving this would be big news for biology. 

The reason why the observation of chiral molecules in space (the news story only reports the observation of a molecule that is chiral not that we can observe the chiral preference) is that it creates hope than we can observe directly whether the chiral preferences of life are inherent in the universe or are arbitrary.  

We don't yet know whether propylene oxide (the molecule in the news story) exists with more of one chirality than the other, but now it has been observed, we can expect to find out as instruments improve. So the big story is that we now have some hope that we can test some of the theories about why life has a handedness preference.