When we went to Svalbard on the cruise we didn't get anywhere near as close as the images in the video feed seems to show. ( Admittedly we were on a bigger ship. )
The question has to be 'What the hell was the captain playing at?' given the evidence from a similar cruise 3 weeks ago seems to imply that they went in much closer than most folk do in inflatables which can quickly get away.
Talking it over with dad we think he's bumped the ice and triggered the fall.
One other point is that we were up on the North-West of the island, this incident occurred in the South-Eastern part.