The hypothetical scenario the paper is built to bound — the only variant of “stable black hole” not already excluded by Earth and Sun survival (charged stable holes stop in Earth/Sun; see the charged-stopping argument). The paper notes there is no known consistent microphysics in which Schwinger discharge operates while Hawking radiation does not — both are quantum pair-creation effects, differing in that Schwinger discharge happens outside the horizon while Hawking radiation is trans-horizon — so the scenario is regarded as close to self-contradictory, but it is not strictly ruled out by that observation alone.