What about Arnold (the singer)?

Hint 1 of 7:

You can always run away by giving him a worthy song title.

Hint 2 of 7:

There are two ways of getting to Arnold.  One path has a slight detour.

Hint 3 of 7:

Look at the boulder there.  It can help crush Arnold.

Hint 4 of 7:

For leverage, you have two items.  One came from Algiers, and the other
could have been used to kill Anton.

Hint 5 of 7:

The ship rib or stalactite will do the trick.  (See the last question
to find out how to get the stalactite.)

Hint 6 of 7:

Now, you need to push the boulder a second time.

Hint 7 of 7:

Go to Arnold and take another exit from the room.