Yes, I understand your point. I don't mean to say that Cthlulhu actively seeks us out to destroy and consume us. I understand that the great old ones are above our morals, but make no mistake, if Cthulhu notices us we ARE destroyed. There's no flipping of a coin or chance for him to be friendly. To be noticed is to be crushed. Since we have to squeeze him into our constructs, I'd say from our perspective he is chaotic.
From some people's perspective, sure, but from others, no. If nothing else, this thread demonstrates how such an entity can be viewed in very different ways, which is very cool. It's the reason I'd allow any Alignment in terms of characters following Cthulhu. On one tentacle, you'd have the insane, the power-hungry, and desperate, those Chaotic individuals who see Cthulhu largely as a destructive force and who hope perhaps to be spared or at least to enjoy power while they still can. On the other tentacle you could have very neutral scholars, those who recognize Cthulhu as an advanced being that ultimately doesn't care, but is worthy of study, propitiation perhaps (hope springs eternal), and that could serve as a gateway to larger cosmic alien forces and understanding. On the third tentacle, you could even justify (at a push) some Lawful followers, who see in Cthulhu and his kin a stronger, purer, more advanced and aged civilization, and seek to learn more about it or perhaps even emulate it.