Most organic molecules are different from it's mirrored version, and living thing usually produce only one version. But inorganic reactions produce an even mix of 50% and 50%. So in most cases it's easy to spot.

Also, some sugars or amino acids are very common here and others very rare, and the commet probably has another mix.

Also, the ammount of isotopes of the atoms (like Carbon 14) is probably different.

There are papers covering contamination prevention and detection for every stage of the mission. There are papers with the designs and intentions before launch and papers with how well it went and their specific findings after return.

Here is one sick paper covering some of the clean rooms https://ntrs.nasa.gov/citations/20230005897

>”Once soft and flexible, but since hardened, this ancient “space gum” consists of polymer-like materials extremely rich in nitrogen and oxygen. Such complex molecules could have provided some of the chemical precursors that helped trigger life on Earth”

That would be some stale big league chew if that were the case. By orders of billions of years. Making it the oldest wad of big league chew we know of in existence. ;)

"I will assume that the experts involved have not taken any reasonable precautions, and learned nothing from the past 60 years of acquired experience in space exploration. I will then ask other non-experts in the field if the experts are minimally competent or not."

I think the article does a good job clarifying in simple words those questions risen by the slightly click-baity title.