This isn't a reflex. This is a living thing processing visual information with half a billion neurons and responding. Isn't that intelligence?
Carl Zimmer in...
How Smart Is the Octopus?, Slate, 2008
...says, "So, is the octopus really all that smart? It depends on how you define intelligence." And he took a stab: "What we call intelligence is really just a set of behaviors and abilities that evolved in our ancestors as they adapted to a particular way of life."
So, intelligence is relative. However intelligent we may view an octopus, it's fair to say, as Zimmer did, "We'd fail pretty badly at an octopus-based test of intelligence."