Nautilus' old lore was that he was betrayed by his shipmates, and an evil power fused him with a diving suit of armor. So he carries the burden of his grudge in the form of an anchor, the one clue he has of finding those who betrayed him. His joke had a double meaning, "Sometimes this anchor just weighs me down" (If he let go of his thirst for vengeance he wouldn't have had to trudge through the depths).
His new lore is this:
All know the tales; all pay the Bilgewater tithe. Since time immemorial, Nautilus has roamed the dark waters off the coast of the Blue Flame Isles, dragging impious sailors to their doom. The armored goliath strikes without warning, his inexorable footfalls churning the waters, before swinging his enormous anchor upward to shatter mast and keel alike. He then pulls the flotsam beneath the waves to appease the wrath of the Bearded Lady.
So now all he is is an evil sea monster? Do all of the "evil" champions have to have any identity and meaning behind their character stripped away, turned into generic cartoon villains?