Aww Lisa,
At least he's still able to help you out.
This reminds me of a lady with dementia who folded the laundry and did dishes at her care home, because she thought she worked there, and never realized what was going on. When she was in the hospital for a little while, the hospital called to find out if there might be any alternative to restraints or sedation. Her regular caregiver suggested they roll a rack of clean unfolded linens to her room. She folded and re-folded that rack to her heart's content, and stayed calm. They just threw the lot back into the laundry after she went back to the care home.
I'm glad you've found a way for him to be/feel useful. He needs that.