I will say that Utopia is a top notch company. I have had two of their backrests. 1 for my Venture and 1 on my wing and they are top quality and very fair pricing. They communicate very well with their customers. They are a Christian company and their business practices reflect that as well. I am not affiliated with them in anyway, just passing along my experiences with them.
I think your correct in which case it is useless, because now you have to have the back seat on and on top of that the passenger has this huge thing digging in there stomach. This one doesn't look very functional. Still a good find though , thanks for sharing.