The Cosmic Hitch (Class-X Singularity) is not a black hole, but a looped cosmic string. These are 1-dimensional defects in spacetime (leftover cracks from the Big Bang) that possess immense tension and mass.
A Type 4 civilization can bend a cosmic string into a loop (a Hitch) and use it to cut through spacetime.
Because the string is thinner than an atom but has the mass of a galaxy, it acts as a gravitational lens so powerful it creates Closed Timelike Curves (CTCs), ideal as an engine core for time machines. By navigating through the center of the loop, a vessel can traverse the CTC and arrive in its own past.