There are little Allen head bolts inside that trigger on both sides. You tighten them once you install the pins and they won't come loose. Friends don't let friends run anti rotation pins.
It was just like you said, so when I finally got some light in there, it all became clear how cinching the screws down pushes the trigger up and against the pins. Gotter zipped up, Locktite and all.
The one thing I'm confused about though is that on top of each screw was a shorter screw, for a total of four screws in those two holes. After I got the bottom screws tight, I put the smaller ones right back on top like it was. No need to reinvent this wheel though, looks like everything's been thought of.