If a “category of claims” has shared causal structure, then the category’s track record absolutely does tell you something about the next claim in it.
It’s not arbitrary. Alien UFOs, Chem-Trails, and Flat Earth are obviously all generated from the same distribution of bullshit: ambiguous or misunderstood phenomena explained by positing a vast hidden conspiracy.
What about Avi Loeb's theory that 'Oumuamua is an UFO with a solar sail, which would explain its apparently unusually flat pancake-like shape?
Every person on Earth could agree that Earth is flat and it wouldn't affect the reality of whether or not extraterrestrials visit earth even a little bit.