The Jacen plot is not a red herring. Abeloth was the main Chessmaster behind his fall from grace...she just didn't do it directly. Somehow she managed to get Lumiya under her control; Lumiya was flying under the Alliance's radar for quite a while, so it's not inconceivable that she could have ended up in the Maw somehow. Then, she sent Lumiya to turn Jacen to the Dark Side; she might have even fabricated the "Tassels" which were telling Jacen to sacrifice someone he loved. As we all know, this resulted in the death of two of Luke's biggest love interests, Mara and Lumiya. Once that was done, all she had to do was kill Akanah, and Abeloth would have Luke all to herself.