Well, actually, he does not. As you can see here, he is rather enjoying bathing in the beam of the lighthouse and not guiding at all:
I guess Cthulhu would like to have a chat with the nice people in the lighthouse. He probably feels lonely in this dark and stormy night after having slept for several eons.
The assumption he just wants to chat is based on the fact that this is another cute incarnation of everybody’s favorite Great Old One, so any sort of harm is highly unlikely.
So remember, children: When a cute Great Old One comes knocking on your door, let them in and offer tea and biscuits, you could well gain a friend for literally all eternity.