Right... so the part I highlighted in red (the two flaps on either side of the back plate pocket) is what I'm wondering about. It just seems like a weird design. Kind of reminds me of a CIRAS vest.
It's great that the included cummerbund is removable, but that little flap would just get in the way and make it annoying to use aftermarket cummerbunds such as:
I'm wondering if their other vest is also built like this.