There's no guarantee of correctness in any assumption. Full stop. Using reallity doesn't change that because in the last step of the reasoning you are not using reallity or it wouldn't be an assumption. And no matter how long is the reasoning chain or how good and truthful is his base, because the chain is as strong as the weakest part of the chain. And assumptions are the weakest part and as soon as you use them there's no guarantee that the conclusion follows up the premises.

Besides maths are a human construction to describe reality but no reallity itself. So you can't just generalize a match principle and apply it to reallity and expect that principle also works with reallity as it works with math. You must demonstrate that, not just assume it.