TL;DR
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The intention of this mod was to dynamically adjust Settlement Defense Rating based on automatron equipment, unfortunately this isn't possible at the moment, and this is being left up as a modders resource and proof-of-concept.
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Automatrons you create provide settlement defense. The defense buff depends on how intimidating your Automatron is. Stronger gear = More defense value. Some pieces don't contribute to your defense value. The base value is 14 defense.

This doesn't change their AI packages to actually defend your settlement. They'll behave just as normally

Essentially... 
Better weapons? Buff
Torso Misc Mod? Buff.
Head Weapon? Buff?
Shoulder Weapon? Buff!
Tough legs?...Buff
Tougher Torso?...i give up. YES IT'S A BUFF


...except for Mr Handy Thrusters. no. no buff. u get less defense for tht POS - Changed it to if you have a "No ___ Mod", to give you less settlement defense. I still don't like Mr. handy Thrusters. They're not intimidating