When a ship is in port, most of the time one side of the ship is alongside the pier while the other side of the vessel is flanked by water. Think of it as parallel parking: When you parallel park, one side of your vehicle is along the curb side of the street while the other side of your vehicle is flanked by the street. If Grandpa had held Chloe up to an open window on the starboard side of the ship, she would have fallen into the water. I recall an odd comment that KW made in one of her media interviews: "I thought there would be water on both sides of the ship". The ship was in port at the time of the incident, so only one side of the ship was flanked by water.
Someone mentioned that pier cameras might not belong to RCCL, but I feel certain that there is other surveillance video of the dock side of the ship at the time of the incident. I'm also confident that there is exterior footage on the ship that might or might not show the incident. A passenger on the starboard side of the ship could go overboard when the ship is in port, and port authorities must prevent anyone getting on the vessel who is not a ticketed passenger and/or shipboard officers, staff, or crew.
OT: DH and I are in cruise countdown mode as our winter cruise (for my 70th birthday) is coming up in one week. We will pack this weekend because DH is working through next Thursday, then we're off for a sailing on Sky Princess