Um, my Powertech main is running around with the Imperial Squad Leader title and I have only levelled the affection of my Marauder's Light Side Jaesa to maximum.
Thats because only the lightside Jaesa counts towards the achievement, not darkside Jaesa.
Loyalty to the Sith Warrior requres: The Beast, The Commando, The Officer, The Treasure Hunter and The Padawan. When you then go and look at the Sith Warrior Achievements. "The Padawan" is specifically light side Jaesa. Dark side is "The Corrupted Padawan"