I think he could have gotten off the ship without notice. Someone on another forum suggested he was trying to duck out of child support and criminal charges. Heck, once the boat is in port, you could jump off one of the lower decks and swim to shore. You could definitely jump off of a Cove balcony and not be injured. I have jumped out of trees/off of rocks at lakes higher than Deck 2. I know he had an inside cabin, but when people are checking out, they sometimes leave doors open. And some of the boats have public decks on like deck 4.
I mean, most likely he committed suicide, but stranger things have happened. Like the guy from Louisiana who fell off a Carnival ship and was found after a couple of days floating in the gulf recently.