Very tragic indeed. I love Schlitterbahn, grew up going to the original every summer in New Braunfuls, TX. Its a tragedy to all involved.
Don't quote me on this (hahaha) but I believe the age limit restriction was removed from the ride after its first year of operation. Also, from the reports I have read, the boy seems to have met all rider requirements. Initial reports make it sound like a seat belt malfunction.
When Verukt first opened I was always leery of why the ride needed seat belts. Any water slide that needs seat belts isn't designed properly. I can't think of one other water slide that has them...I wonder if this attraction will ever reopen. It has already been reprofiled once.