A boom kicker is not the same as a traveler. An installation like this would probably benefit more from a traditional rope vang pulling down rather than a kicker pushing up. Based on the triangular shape of the attachment, hauling on the line would not only pull down on the boom, it would want to centre the boom, and this would provide no ability at all to control twist. At least with a rope vang, you could set up a bit of tension on the boom, and use that mainsheet installation to more control the boom position. Either way, its not a great sail trim solution, rather it looks like it was convenience driven.