I dont think they are saying it is a superconductor. Conclusion from abstract:
>> These findings are important in understanding LK-99’s structural and electronic properties and provide a strategic compass for the development of high-TC superconductors.
Until someone makes it and it is superconductive as confirmed by neutral third parties I will continue to be doubtful. Words and simulations are cheap here, and the proof is what matters.
It doesn't appear that the abstract makes any claims about LK-99 superconductivity at all. Unless there's something in the inaccessible full article that contradicts the abstract, I think the submitter misread "semiconductor" as "superconductor".