Thank you! And thanks for clarifying the cable's purpose and position.Great build so far! I think this is the best method to use for the armor, because the diameter difference of the grommets and the plastic screws allows the plates to move slightly and sit "naturally" on the vest/torso.
They used that cable to power the chest light, which had a power source (as you correctly assumed) in the left thigh pouch:
View attachment 170198