JD Jones, of SSK Industries, maker of self-professed "hand-cannons" developed a scope mount that is called the "T'***"...and it stands for exactly what you'd think.
The notion of any optic mounted to a 500S&W revolver with but a single screw seems self-evident to me; a bad idea from the outset. Take a look at most of the scopes mounted to very powerful handguns and you'll find they have three, and even four rings, to secure them and improve the life of the scope. I would sooner shoot such a gun with open sights than with an optic secured by one screw.
With all of that being said, I started reading the EOTECH website FAQ's and I kind of doubt it attaches with just one screw. I submit for your review, the picture in the header of the following website.
http://www.eotech-inc.com/productfaqs.php
With a full rail attachment, this unit appears to be secured with 2, or possibly 3, screws. I guess it depends on how your revolver is set up, but even if you can get 2 screws through the sight to secure it, I can't begin to think of this as a good option for a handgun.