No way. Don't believe it. What you are suggestion would be a revolutionary feature that we would see EVERYWHERE. To think that all the chainsaw-pants manufactures and retailers "forgot" what it's for is just plain silly.
Though it might provide that back warming sensation for you, I don't think it makes a difference anyone can count on. If back warmth was the answer, everyone would be wearing fuzzy fleece belly wraps to keep their lumbar region toasty. No one does that and no one recommends that. Seriously- if this was the case, I believe every UPS and FedEx employee would be required to wear them, TCIA and every insurance company would require back warmers, the workers comp programs would give discounts if your workers wore them, etc.
Ummmm..... Maybe if you get out of the dark ages and find some documentable proof somewhere online and share that with us young bucks, we won't banish you to a rocking chair on the front porch to do your whittling....in a back warmer!!
love
nick