1. I really like both Peace and Magician. Short of a cruise ship and my own boat, Peace has the best food on the seven seas.
2. As far as safety rules, I was recently involved in a discussion about what happens when a dive trip is interrupted by a diver injury. There are a bunch of divers who pay good money to go out and do three dives. Some of the divers may be on vacation from far away. If the trip is interrupted because a diver is injured, the other divers don't get to do the dive for which they paid. Is that fair to them? Clearly, if it isn't the boat's fault, then there is no basis for a refund or a "rain-ticket" as the boat should not suffer.
Thus, there is a particularly good reason that a boat or charterer might want to set some fairly high safety standards and gate and return times.
I must, however, note that I personally do not see any reason why nitrox should not be allowed. The justifications cited do not persuade me. Unless the DM is checking and approving each diver's dive plan, I see no need for the DM to be able to check a plan based on nitrox. While there are a few more places where a diver could make an error in planning a dive on nitrox (error in analyzing gas, using the wrong table, looking up maximum depth or computing oxygen loading), those, IMHO, are insufficient to make nitrox risky enough that it might impair other divers' dives.