If I see someone taking the gold block and throwing it in the ocean. Can I then KOS that person, or would that be an invalid reason? I know it says in the rules that throwing the golden block in an unreachable location is a valid KOS. But what if that person just hides it? Is it valid then?

If I see someone taking the gold block and throwing it in the ocean. Can I then KOS that person, or would that be an invalid reason? I know it says in the rules that throwing the golden block in an unreachable location is a valid KOS. But what if that person just hides it? Is it valid then?