As you can see, it's aligned. To me this is one of the most secured pieces.
As I wrote in the first post, I originally fell into the same trap. After I read that LiegePrime managed to place the waits plate securely, I tried again and you are actually supposed to shape the ball hinges of the plate so they go over the minicon ports. The result of this was a solid plate so the biggest flaw that I found on the gestalt was just me not positioning the piece properly.I think the waist plate is a piece of crap. The problem is it's ball jointed, not hinged, so it can't move up along with his thigh. Coupled with the fact Onslaught's knees (thus Bruticus' thighs) have Mini-Con ports right at the top, moving the thighs forward will inevitably pop the waist plate off.
The only real design flaw that I see in the set are Onslaught's missile pods at the individual figure level. They hinder articulation severely and seem to easy to pop off despite looking pretty cool.