This achievement is very simple to unlock, but is
MISSABLE!
Obviously, do NOT kill or use a take-down on Slaw when you first meet him very early in the DLC.
Later, once you are in the Palisade Blade-01, make your way to the second floor of the facility. You will want to reach a part of the map labeled, "WEST MAINTENANCE CORRIDOR 2F". The screenshot below shows my character's location where precisely you will want to navigate towards:
There are a few ways to reach this area, but the simplest and quickest is to walk/stealth over to the double doors marked "WEST CORRIDOR - Maintenance and Utilities" after arriving on Level 2 through normal progression.
Provided you didn't kill or take-down Slaw earlier in the game, he will be found here and after a cutscene is triggered with Adam speaking with him, the achievement will unlock:
Feel free to oblige Slaw's request to knock him out after he unlocks the nearby security door and camera.