I find scott michael particularly complete when he describes fish familys (like this list of morays) and how to care fore them. I would guess that he has first dibbys on many of these fish, cuz he can. Ever see his talks where he shows all these ambon devilfish, etc- , then he says he had them in his aquarium. I would guess he somehow collects them after he photographs them or he has some special connection to get them.
However just becase he writes about these fish doesn't mean you can get them.
I would suspect a good majority of the fish he described never makes its way into the hobby or to the USA. I would guess that rare fish are collected all the time, they just don't come to amercia (mainly because places like Japan are more than willing to pay top dollar for these rare fish-check out splash to see their prices), or if they do its one or a few fish.
Next, if a rare fish comes into a wholsaler, they know its rare and it goes immediately to a high dollar place. Marine center does get rare fish and they know what is and isn't rare, and they ask prices accordingly. Randy knows what comes in and if he says a certain fish doesn't come in...then I would bet dollar to donuts the fish doesn't come in.
Case in point are the rhinopias, marinecenter has one, their asking prices is over $1800, they know its rare, the wholsaler knew it was rare,
Last point, I've prolly never seen 95% of the morays in scott micheals book in any store in my 18yrs of fish keeping
my opinion
frank