Mmmm... I just don't see it as that different from hiding under a rock. Or the humble hermit crab.

They're ambush predators and from the looks of the video there isn't much cover to be found in that lagoon, until people started tossing halves of coconut shells in.

If they built a man made reef in there i'm sure plenty of animals would flock to it and put it to use.

That said i've always had the impression that squids and such are more intelligent than some people believe.

I'm just not convinced that this qualifies as "tool use".