Can I save the claptrap in the cage?

Apparently I must save this little fella before I can get the Old Haven SDU. But how? There doesn't seem to be anything interactive around it, there doesn't seem to be any way to get up there, there doesn't seem to be any way to interact with the claptrap.

What should I do then?

You need to progress down the main story line's quests until Tanis gives you one that is entitled, Not without my Claptrap. This is one of the last quests before moving on to a new zone so it may take a few before you receive it, but I am unsure of the exact number between the one showing on your screen (the one where you put the fires out) and the one you free the claptrap on. It is not more than 1-3 however (its often hard to tell main quests away from optional, hehe).