The theorem mentioned here, that in a finite range exotic matter, violating the energy conditions is necessary to form CTCs, i.e. that spacetime is suitable for time travel, is simply not true. Whoever supposedly proved it.

It has long been known that regular counterexamples, i.e. finite time machine spacetimes with normal matter, satisfying the energy conditions, are possible. For example this: arxiv.org/pdf/gr-qc/0503077.pdf

The theorem mentioned here, that in a finite range exotic matter, violating the energy conditions is necessary to form CTCs, i.e. that spacetime is suitable for time travel, is simply not true. Whoever supposedly proved it.

It has long been known that regular counterexamples, i.e. finite time machine spacetimes with normal matter, satisfying the energy conditions, are possible. For example this:
https://arxiv.org/pdf/gr-qc/0503077.pdf