On the facts as stated, in this case I would press for compensation, and ultimately I would expect to get it. The operator has a reasonable duty of care in what is a well recognised situation, and he didn't comply with that duty of care.
However, I can think of two liveaboard trips I've done which didn't work out as planned. On neither did I or anyone else (so far as I know) even contemplate asking for compensation. One was in the Irish Sea, when heavy seas at the dive sites prevented us from even leaving dock for a full two days. Our attitude to that was that when you plan on diving in the north Atlantic you know that you are at the mercy of the weather. If the boat had never set sail then I would have expected a full refund, but given that we did go out I expected to pay in full.
Another was in the Red Sea, when a storm one night was so severe we lost one compressor overboard and the ship was sufficiently damaged that we had to go back to port, losing two days of our trip. We all felt grateful to have made it back at all, and reckoned that the operator's loss was much greater than ours.
There is a culture, part of the litigious frame of mind, that if something has gone wrong someone must be responsible, and that person should pay compensation. I believe we in Britain have not so far gone too far down that track, certainly not as far as the Americans seem to have.
I used to work at a company in the food industry, in England. It was a summary dismissal offence to come to work when you knew you were ill and probably infectious. Despite that, they had a very low rate of malingering.