Note this is about phase metastability, and not RT, 1ATM high Tc. They don't claim that in the actual article, just that phases like high Tc phases survive at 1ATM. There is __no way in hell__ that they would have published this, if they hadn't already tried the viable RTS phases, and they didn't work. It would have been literally giving away a Nobel prize to any other group which could race to do it first.