I think it's a bit more than a random prediction, it's more like a heuristic.
Imagine the tree of all possibilities and all subsequent possibilities below those etc. It's just too vast to explore. The ideologue is not random a path through the tree but biased in a very human way with pessimistic assumptions about human motivations and behaviour that are sometimes true. A heuristic can be valuable without achieving more truth than fiction, just better than random.
> ideologically motivated reasoning would be "The US is about to collapse because Biden/Trump is president"
What I have in mind is the ideological forecaster would start with a set of assumptions and try to justify them against the odds e.g. they assume "Biden/Trump is a monster", they adopt the specific mindset of this monster and interpret the known events, which seem entirely innocuous on the surface, as contributing to a larger nefarious strategy and work through a chain of consequences to arrive at a compelling theory that hangs together. It's like exploring many moves ahead in chess without an evidence based goal function justifying continuing down a specific path.
A reasonable individual might not presume others are monsters or pursue a line of reasoning so unjustified for so long. The heuristic works because sadly "X is a monster" and "innocuous actions are actually part of a nefarious plan" is sometimes true.
I'm essentially defending conspiratorial thinking as a good thing in an adversarial situation so long as it's integrated sanely and not allowed to rule the day alone. If you don't have ideologues of different flavours in your intelligence unit, you might need to create them.