When Krawk Island disappeared, McGill and his pet Warf were the only inhabitants left behind in a small hut. He took charge of the efforts to locate the island and bring it back, eventually becoming the Governor of the restored island. At some point in the future, he will have in his possession the prison the Claymaker is held in, at which point Aurrick will accidentally release him.
I can only be imaginin' what it's like out there, considerin' that whatever did this to the island is still roaming the waters. I've heard rumours that a sea monster may be responsible, but you know pirates and their tall tales. If nothing else, with Krawk Island's riches scattered to the four winds, I'm certain you've come across plenty of... fringe benefits, no? Hehe. Let's try not to get too distracted, though... savvy?
Not many are willin' to cross choppy seas just fer a goodie bag, I'd say you earned this loot! Looks like the voyage left you knackered, so feel free to rest yer weary bones here for as long as you wish. Me mansion doors are always open to fellow privateers!
McGill may be somehow related to the crew of The Surly Peadacle, who helped locate the island.