Not a stupid question by any means. I come up with some off the wall things.
But they work in the field.
Its part of the carry system. Pretty much self designed. Notice the sling stud on the bipod. There is one on both sides. The bipod is constantly attached and the sling is out of the way for a rushed prone shot if necessary.
These heavy rigs are way more than a single shoulder can stand for very long. Thus this innovation.
I carry across my shoulder with the gun in front. Quite nice I'd say...
Kind of Hollywoody but functional.