Perhaps a charitable interpretation of that statement is "there are years of work to go from a proof of concept to a usable product". Even if LK-99 is some kind of a superconductor, there are a whole host of daunting technical issues that will need to be solved. For example: how do we get the yield up? How to turn it into a wire? If the material is not ductile, how to form the wire into a useful shape? How to reliably couple to the wire? How does the material age over time and and humidity? How to deposit and pattern it as a thin film?

We have a lot of arrows in our quiver to shoot at these problems -- I would be optimistic that the promising applications of a room temperature superconductor would attract plenty of investment and talent. On the other hand, I imagine it may take years or even decades before we have answers to these hard questions. As the quote says, "there's no guarantee" that we can solve them, because right now we know so little about the properties of the material at this time. Of course, that is no reason to throw in the towel right now!

I don't think it's too hard to imagine that other characteristics of the material could indeed get in the way of practical applications — perhaps brittle-ness or difficulty of manufacture or challenges in making it in the appropriate forms or ...

Could be extremely expensive or impractical to produce at scale, could be extremely brittle, etc.