Whether or not it is a Coast Guard rule (doubtful), fact is I only know of very regular customers / friends / family / ex-employees who get to dive without the DM off commercial dive boats in Hawaii. For the vast majority of visiting boat divers, you will be diving with the DM. I truely believe this is because without a local guide most visiting divers don't see the cool stuff so operators make sure they are shown some cool stuff. For the most part, divers that have negative experiences in Hawaii are the ones that did not dive with a local guide.
Guess what I do for a living?
Guess what I do for a living?