If vents exist on the seafloor of Enceladus, and all the methane is from life in vents, and then that life survives the long journey to the surface through the ocean and ice, and then survives massive depressurization when it hits vacuum, and then doesn’t get murdered during the still high velocity flyby, then it only takes 100 such flybys, which is huge number.

Some papers are worth writing because it’s good to crunch some back of the envelope numbers, but we don’t always have to take them seriously…