I think it was a freak mishap, and possibly, the plastic piece was already damaged and just waiting for some stress to pull apart.
You'll see when you get a replacement and try to insert it, it's a tight fit and could of held, even cracked, for a while. Hobie made the piece with the 2 plastic bolts on each end to shear instead of the plastic breaking, but I've yet to hear about someone shearing the bolts. I think the plastic pieces (at least new) hold too well to stress the shear bolts.
Also, the aka braces could easily get damaged when the akas are not on the boat, so we've started to use the ball bungees that we carry on the akas to secure "stuff" to secure the bar to the akas when not in use. After sailing, we disassemble the boats (up to 3 so far) and just put the akas in the back of our pickup to transport, then rinse off everything at home and properly put away. Keeps most of the sand and salt out of the bags for storage and the trip back to the beach.
You're only the second person I've heard that's turtled an AI. The other did it while launching with the amas folded in.
I'm about 175-180 but seem to carry most of our gear including an anchor (for snorkeling) and emergency gear, so probably getting closer to your weight. We've also had many different size/weight people in the boats. When the wind gets up to 15-20's here we get at least 5' wind waves and have never felt that the boat wouldn't "hold together".
I think the most jarring the boat takes is parallel to it's side so crossing the next wakes at angles should stress it less.
So, just, get it fixed, and go back out and have fun.
And when you're not boating, plan out what you might need for self-rescue, and to minimize damage and loss and to continue your sail. Then share your ideas here (or at the KFS forum) with the rest of us.