Okay. Throw out all the stuff about hygiene, crew members cooking, and bedding. Most respiratory viruses are spread by hand-to-hand or droplet contagion. Staying in the same room almost certainly didn't affect things, because most of these viruses are short-lived and killed by a minimum of light, dryness, or cleaning agents. They are passed by hand-to-hand or respiratory droplet transmission.
So the question becomes, if the dive op or boat administration knew that some of the crew were ill with a respiratory illness (aka cold), should they have cancelled the trip? What would you have thought if you had arrived at the boat and been told, "Sorry, you flew here and we know that, but we're sick, so we're not going out." I suspect you would have been even more angry.
On a liveaboard, you have a limited number of crew, and you can't just phone into town to replace them if they are ill. If there's an obviously contagious respiratory virus on board, the crew has to make a decision as to whether it's better to take you guys out for whatever diving you can get, or cancel the whole trip and have you eat the airfare you spent to get there. They decided to try to get you as much of a dive trip as they could, even considering that they were sick and probably weren't enjoying working very much.
It didn't turn out well, and it seems to me that the company that owns the boat might well have offered some compensation, even in the form of a discount or free dives in the future. But put yourself in the place of the captain . . . He's got, what, ten divers who want to make a trip? He's got a sick crew, who are dragging themselves around trying to set up gear, break down and clean gear, cook and clean up after a crew of people who are on vacation and thinking of nothing more than having a great set of dives. He's doing what he can to provide that. People got sick, and are really unhappy. Did he make the wrong initial decision?
On my trip to Indonesia, one of our fellow travellers got on the airplane with the beginnings of a cold that she knew about. In the course of the trip, half of us got sick and missed one or more of the most amazing, magical, fabulous dives we'll ever get a chance to do. Should we have sued her?