I don't think it's a crackpot theory. The basic idea is that the gauge group is the group of rescalings of the units of money, and arbitrage appears as curvature in the gauge field, i.e. you end up with a net change when you parallel-transport money around a loop in the (discrete) space of assets and time.
It's a trivial statement since many equities are correlated on a multidimensional manifold of characteristics. Jim Simons was just early and now rentech is nothing special.
Rentec is still world renowned after pioneering the quant business 40+ years ago. I don't think the rested on their laurels with some easy thing that they just stumbled on early
He once "leaked" the idea that Jim Simon's trading success came from his use of ideas called "gauge theory" and "fibre bundles".
I forgot the exact timestamp, but you will have to watch the entire interview to find that segment — https://youtu.be/zVWlapujbfo