Hmm. Maybe they get some twist; design seems pretty simple. Have you tried sticking a threaded bolt through and seeing if that makes a difference? But it looks pretty snug.
Here's mine (minus any disconnect):
Don't see why your's would snap but not mine, except for the orientation. With a stud and urethane spacers that rod can wobble around a bit and not stress the nut much at all. To fit a disconnect to a stud top most of the aftermarket disconnects seem to use a bracket that attaches at the top of the hole in the bar, with two ears that hang down, through which a bolt goes with the eye of link in the middle.
Maybe a heim joint would work better in your setup than that rigid eye.