>Why is the former political and the latter not?
In that example, I'd say neither one is political. Now, if the one side started saying "Blue-skyers should be deplatformed", THAT would be political.
>Here, you do not really explain why the intuitive thinking used by other authors (extrapolation) is less valid than the intuitive thinking you suggest
I suppose if you really want to get down to brass tacks, my "contraceptives are like bacteria" comment was an instance of paradeigma, a rhetorical procedure popularized by Aristotle in which one attempts to help guide one's audience by presenting analogous anecdotes.
The difference between that and the extrapolators is that the extrapolators, at least in most cases I think, are unaware that they are falling prey to an unjustified extrapolation. None of them have come out and explicitly defended the implicit logic "Inverse correlation for the past several decades => inverse correlation forever". If someone DID want to explicitly defend it, they might use paradeigma right back at me, saying something like, "The inverse correlation is like the sunrise. We've observed the sunrise for a long time, and the sun will certainly continue to rise". Of course, such a rhetorical maneuvre would be unlikely to win many debate points, because the audience isn't stupid and can clearly see that analogy's too much of a stretch!
>it is about the words that are not there
But then basically you can twist anything at all into being political. I could say "1+1=2" and you could say "That's political! You're trying to imply something about binary genders, since you didn't explicitly throw out a disclaimer that you aren't trying to imply something about binary genders!"
Not that I'm trying to accuse you of consciously doing that... I think I'm guilty, myself, of sometimes reading politics into things that are apolitical. It can be particularly tempting to subconsciously categorize threads into teams, like, "This guy is X party and is on my side", "This guy is Y party and is the enemy". I've been trying recently to stop doing that, because I believe if I can get past that, there's a lot to learn from the people I thought of as enemies.