In Ch. 37, Quirrell explains how he found Harry:
“and no blood purist is likely to think of consulting a phone book”
Conditioned on Lord Voldmort being a blood purist, this is evidence for Quirrell not being Voldemort (probably the intended interpretation). In fact, this was evidence for Lord Voldemort not being a blood purist.
This is not quite phrased correctly. While I know less magic than the protagonist (having not attended Hogwarts for a year), I know far more physics and mathematics than he does. I am also privy to world-building knowledge that he isn’t. For example, we know about major artefacts:
The Elder wand has been repeatedly featured in the fic, but neither Harry!Riddle not Voldemort!Riddle are aware of it yet.
We also know little trivia:
Tom Riddle’s middle name in this AU is Morfin, not Marvolo. Knowing canon this tells us something about Merope Gaunt’s relationship with her father and brother.
In conclusion: it’s not enough for us to think of a solution, we also need to explain how Harry can think of it. There’s no point in simulating Harry’s smarts on my hardware, I can use my own smarts. But I do need to simulate Harry’s knowledge.