While this statement appears to be rooted in common sense wisdom on the surface, I happen to not agree with it completely. There have been times when commercial captains have refused to go out "due to weather" but I still went out & my silly little boat did fine on that same day. when only one boat is going, it makes me want to reevaluate the situation and give greater scrutiny, but it is not an automatic hard no for me to go with those guys that day. This applies to other types of boats as well, not just the dive guys....
Rule of thumb for you in the future. If EVERY charter except one is not running, you don't want to be out there!