What am I missing?
I talked to an engineer from Cequent Performance Products (the maker of Reese weight distribution products) this morning. He told me that they had never heard of an issue with a frame manufacturer's warranty. Secondly, he told me that there are only two ways to install a duel cam sway control bracket and that is to drill the holes and bolt or weld.
If everything I have been told is accurate and I believe that it is, it appears that Dexter Chassis Group could potentially void their warranty if a problem came up but since none has, the issue seems to be moot. If someone wanted to be super cautious, they could weld the brackets rather than bolt them.