[papertyger]

In that these inferences don't violate or contradict any known facts and can be considered a valid possible consequence of those facts.

Sure they do. Furthermore, such inferences camouflage the fact conventional "science" threw in the towel on abiogenesis a long time ago.

What's more if you can't confirm your guesstimates, what makes you so sure Fermi estimates are any better than the guy looking for his wallet under the street lamp, because the area he lost it in was dark?

Finally, unconfirmed, as opposed to disputed, planets are nowhere near analogous to attempts to make "life" just another mundane physical process.

Showing me a bird on a fence post does zero to explain the turtle, even if it's the exact same fence post.

The sad fact is this area of science is tainted in the same way as "gun control" advocacy; forget whether the thesis is verified, plausible is good enough....just assume it's correct and legislate accordingly.

[AnotherUnixGeek]

just assume it's correct and legislate accordingly.

What legislation? SETI and similar projects have received some government funding but also plenty of private financing. Mind-exercises like the Drake equation are just intended to provide some initial framework for research and discovery - they don't deserve the uncomprehending awe the press always bestows on things like equations, but they do serve a legitimate purpose. Without such things we'd never have bothered looking for or finding extra-solar planets.