I thought someone once said it was to aid in installation of the couch at the factory.
I'll have to look tomorrow, but it is possible that is one very large piece of furniture. Can't remember if it's two back to back seats in one molding, or if they are two separate seat bases...
I've wondered what that handle was for, too. But after thinking about it, if you notice, there's no hinge on that seat cushion, so it seems vulnerable rising out of the boat on onto the highway if traveling at 65 - 75 MPH. So, I thought I'd use it to put a strap to and go across the seat to hold it in at highway speeds while trailering. I might be totally off base, but I sure can figure out what it would be for. An "oh sht" handle? I don't think so since it can't be that sturdy, just attached to another flimsy plastic storage compartment.
We've got a 22 SSLX and found that the space between the captain's chair and the bench was a little too narrow. Two bolt hold the handle on, and it came off in about 2 minutes. No big deal, and it will never be missed!