I was on this cruise too. Fortunately we were back on board having gone to Blankenberg independently and were in the Golden Lion Pub awaiting the 4.30 Trivia Quiz when the incident happened. As we were on Deck 2 (with windows quayside) we were on hand to watch the entire proceedings. Apparently there were 22 coachloads unable to reboard until gangways were reinstated, some were in the coaches for almost 2 hrs. Could have been very nasty had anyone been on the gangways. A thunderstorm had caused the squall.
Incidentally, the weather was very warm at times - I ended up with what looked like a heat rash above my ankles. Next day in Holland we met friends in Scheveningen, one a nurse, who said it looked like burst blood vessels. Now back home and online I have 'googled' my symptoms and discovered it to be Golfer's Vasculitis, caused by a lot of walking (miles, compared to what I normally do!) and heat!

I think I will live ok!
By the way, this was our first cruise and we thoroughly enjoyed it. What a magnificent ship! The sea was amazingly calm, I didn't feel any movement at any time! And the sailways from Rotterdam and Cherbourg were incredible.