There's some naïve humor in this. I mean, seriously? You do think that this sacred rock is a threat to Bitcoin? I've read that the people in Sri Lanka has good access to electricity but it has not yet reached 100%.^[1] And how many households does this rock actually provide free electricity to? I guess none. So before we talk of this rock threatening PoW coins, let's first consider its better and more immediate use.

Well, other than this rock, we actually have unlimited energy sources. We'll never run out of the sun's heat, for example. Neither will our wind get exhausted. We also have unlimited atoms for fission and fusion. And so far, Bitcoin has never been threatened by all this.
 
[1] https://ourworldindata.org/energy/country/sri-lanka?country=~LKA