Hi Ed,
An interesting idea to be sure. You’re indeed correct about trying to cool the mass of the beans+drum. It would take awhile and some horsepower. The largest downside would be repeat roasts and your beans cooking longer than you would like. Your drum would be no longer hot to start your next roast and your roasting cycles would be very inefficient and delayed. To my knowledge no one has ever created such a thing, and ..I’m about to make an argument that you don’t need to.
So here’s why. I can easily sympathize with your comical impressions of people losing eyes and permanently getting disfigured by metal and coffee at 600F. Made me smile at that. I remember personally, upon my own foray into RK roasting back in 2003, when I was a customer much like yourself and not running the business, thinking almost nearly the same thing. The first time I saw the roast process underway, I remember thinking, I’m surely going to burn myself to death. I’m not sure I can safely manhandle all that hot equipment without causing mass carnage to myself and others.
After having watched Ron roast and show me the technique…with only 1 glove on the left hand (if you’re right handed) I really wasn’t sure. Ron assured me I only needed 1 glove on my non-dominant hand.
After trying the technique, it’s really quite easy to handle. Opening the drum with your gloved hand is a simple one-handed operation. The whole assembly gently lifts up and spins rather comfortably in your hand and with a simple flick of the thumb dumps the coffee into your Model T cooler or cooling contraption. And the hot drum immediately goes back to the refill station to get loaded again for the next roast.
I can tell you, now after what..10+ years…that the operation is completely automatic and I do the whole process without having to think about it. In all that time..I’ve burned myself 1 single solitary time and that was because I didn’t pull my glove up on my wrist and when i leaned over for something my forearm grazed the drum. I promise you. Getting burned, should it happen, will only happen once. You learn real, real quick not to do that again 
And also nobody has been impaled as yet. Though I might make that a goal for one particularly irritating neighbor.
Seriously though, it really isn’t, in my opinion, a point of consideration at all. I teach some 25 new roasters a week to roast with this technique and there are nearly 10,000 RK roasters around the world, and none have any major issues with the method. Most describe it as very easy and flexible. If someone were physically impaired and had limited use of their hands/arms…then I could see an issue.
There is a certain technique, which I will drill you through on the phone if you would like. I will encourage you, once you get your roaster built, to drill through the motions while everything is cold to get the feel of it down. After a few times running though the motion, it’s just like riding a bike and without injury to yourself and bystanders.
Call me if you would like and I will walk you through the process, and through any questions you may have. It’s what I do!
Thanks so much!
Shane
And also nobody has been impaled as yet. Though I might make that a goal for one particularly irritating neighbor.