I read the study. It's from the same uni I did my Masters in Astrophysics at.

It was a purely mathematical hypothesis paper.
There is no evidence of close time curves being any more real than multiversal theory. The publication is a mathematical approach to if Einstein-Rosen Bridges actually exist within the physical world.

If a CTC is physically proven to exist, then yes, this study has some merit. But as far as current human knowledge goes, this is on the same wavelength as string theory, multiverse theory, or the death of the universe.