Not defective...
I would just tuck it up under there where it's supposed to be. I see no need to glue it. The part that is curling back out is never seen as it's always under the chest armor when correctly positioned.
I doubt it's even designed to be glued at all. They weren't on the DX12.
Excellent.
Glad you like yours. I'm 90% sure I'm gonna sell it. I would need to fix the abdomen if I was going to keep it, and that would mean damaging the figure. No way I can look at the stomach now the way it is, knowing exactly how to make it better.
But the small head, wide shoulder thing makes me feel even more helpless. Nothing I can do to fix it. Absolutely nothing.
My pic makes it look decent because angling the body disguises this look: