Realistically, the cruise line will probably settle. It's in the best interest of the company to be apologetic to the family in this tragic situation. Remember that Disney settled for the alligator incident at the Grand Floridian beach a few years back? Disney wasn't really at fault - they had signs warning not to swim.... but with it being dark outside, the beach open, and no physical barrier, accidents happen.
I work in architecture and safety is a huge part of my job. In addition to complying with code and ensuring guardrails exist where required and are the appropriate height, you have to put yourself in the headspace of the user. In one situation we had a railing above an atrium space, and the proposed design called for a black floor-to-ceiling stage curtain in front of the railing, blocking off the atrium below for lighting and privacy. They also wanted bar-height tables in front of the railing (obscured by the curtain). This posed a safety hazard because the curtain blocked the view of the atrium below, providing a false sense of security - if someone were to lean on the curtain expecting a wall beneath, they would lose their balance and potentially fall. Add to that bar-height tables.... you're taller than the railing now and if a child were to stand on the bar stool, they could take a tumble and potentially fall 20 feet to the atrium below.
So in this situation, the glass is providing a false sense of security. In the night photo of the crime scene, it's hard to distinguish between the open panel and the closed panel. Large operable windows on an 11th-story pool deck pose a safety risk.
Royal Caribbean should assess the situation - perhaps add locks to the operable windows. If they're open during the day, the crew could shut them at dusk.