I am not a physicist, let alone the right kind of physicist, but from the abstract it looks like the transition temperature is 35K. That is a long long way away from "room temperature".
> We have also observed that some phases remain stable without pressure at up to 300 K and for at least 7 days.
300K = 80F
It doesn't superconduct at 300 K, the metastable phase can survive heating to 300 K and superconducting will resume when cooled back down to 26 K.
"Some phases" (a few molecules?) appeared to have to be stable at 300K for a week. Whatever. I've been writing and reading about cold fusion hype since the 1980s, still waiting for my maglev vacuum cleaner.
Phases typically imply a thermodynamically large quantity. It makes no sense to describe the phase of a handful of particles.
Keep reading: “We have also observed that some phases remain stable without pressure at up to 300 K and for at least 7 days.
Iron selenide in those phases does not superconduct at room temperature. The authors have a "strong belief" that other room temperature high pressure superconductors will retain superconductivity at atmospheric pressure using their technique even though the one they studied doesn't.
The usual Fairbanks room temperature superconductors.