Ok, as much to your dissatisfaction as this is going to sound..... this is a grey area. Yes, besides the belt, that is all that holds the two together. The CRL even states the ab button does NOT need to be functional. If you look at movie snap shots this section is mess, inconsistent. It's the entry point of the armor so the most prone to look all jacked up IMHO.
So, what to do? You can leave it be, or as I've seen others do make a tongue and grove connection between the two. Adam Toy in my garrison did, came out pretty cool.