At some point, however fact-based, every speculation is a form of fiction, so the line is blurry ...
> The title and the abstract suggest they take this possibility seriously, which is ridiculous.
... but I'd say it's I think the idea is to take some serious and very realistic bits that have a vanishingly low probability ...
> We show that 3I/ATLAS approaches surprisingly close to Venus, Mars and Jupiter, with a probability of ≲ 0.005%
... and then walk from there as rigorously as possible.
As they say, "largely a pedagogical exercise".
There's still a line between the hardest hard sci-fi story about a Boltzmann brain and a fact-based thought experiment computing probabilities for a giant marshmallow to spontaneously appear in the vacuum of space.
