I think the USCG prefers to stay out of personal disagreements.
For instance, those Florida drift dives really have no alternative to someone driving the dive boat while divers are in the water. But in the NE, after one operator ran over an instructor who was under the boat (serious injuries) there was extensive discussion that "the" engine key should go down with the divers/divemaster and literally only an "in emergency break glass" key be kept on the boat.
So which is right? Spin the prop while divers may be under the boat? Or let them drift away? (Or just put a cage on the prop, the way NE lobstermen often do.)
Sometimes you have to remember: You are your own divemaster. You need to think about these things, and if there's any question, speak up. Ask the captain what they do on the boat. If you don't like it and they don't want to accommodate you? Take another boat.
Ask the USCG how many "Gee, did we lose some divers?" they recover, or someone recovers, in Florida all the time. Flags, markers, whatever.
No regulations needed.