I like the idea, but it wouldn't seem appropriate for a full days wear. I have seen stock picker carts used that have a folding seat attached; beats dragging a chair along.
My initial concern is dependence on the waist belt for support over a 8 or 10 hour day.
When back braces were first sold at retail, many people took to wearing them full time. Like a cast on your leg, muscle tone deteriorates if not used something past minimal. That brought a period of lower back complaints. Shortly there after, the recommendation was to tighten the suspension just before a heavier lift and then loosen.
In reality the back brace is rather a placebo, reminding user of correct posture when lifting, more than actually keeping your parts in place.