One thing occurred to me. Recently there was a meteorite recovered from Antarctica which purportedly had trace fossil evidence, and that the lithological make-up of the fragment suggested it was of Martian origin. Let's suppose both observations are correct.
Might "living molecules" have evolved on a young Mars and a young Earth simultaneously? If so, were the physical conditions and time frame similar? If both are of an "intelligent design" origin, then why did a designer place life on a planet (Mars) destined to become lifeless (or nearly so)?
Without arguing the fundamental correctness of the statistical calculations, and the fundamental premises upon which they are based, how does the equation change if we begin a more-or-less constant rain of trans-solar system material, some of which may have been carrying organic molecules whose origin may have been from some distant part of the solar system is some distant time in the past??? Then, the physical constrants of the Earth's temperture or chemical composition become less meaningful. In other words, you don't need to begin the process on Earth, if your are "seeding" life from other parts of the cosmos.
The test of the "seeding" hypothesis would be if organic molecules can be detected on "dead" planetary bodies, such as moons, asteroids, meteors, etc.