In August I wrote: A few years ago PCW Davies persuasively argued that Earth life more likely started on Mars. Last year, Napier and coauthors argued that comets are an even more likely source: A single comet of radius 10 km and 30% volume fraction of clay contains as much clay, to within a factor of around 10, as that of the early Earth. However, our Solar System is surrounded by about 1011 comets forming the Oort cloud … Whereas the average persistence of shallow clay pools and hydrothermal vent concentrations of clay on the Earth can range from 1 to around 100 years, a cometary interior provides a stable, aqueous, organic-rich environment for around 106 years.
I just added to the post.
Life can exist in ice. See http://www.youtube.com/watc... .
How you "tend to think" of comets is not very relevant - they can be warm enough inside near a hot star, near thousands of close stars, and after being coated with radioactive material from an exploded star.
Me, I don't get how life is supposed to form in a comet. You say it has an aqueous environment. I tend to think of them as "icy". And life has moving parts. That's why freezers work.