Well, I guess if he likes to fight without shield in ranged combat, I suppose he likes the lower encumbrance?
Also, while it's not perfectly logical, why extra items?
Just create a normal riot armour with shield, and have an option to put it on your back, invisible with no bonus.
I mean, if that logic was a problem, we should have been able to switch it out right now, or change the panel in a protective vest.
We can't.