I think I can guess UL's position. It would go something like this:
"UL tests to nationally recognized standards, and does not endorse any particular brand or technology. UL is not prepared to offer any opinion on this particuler product. Indeed, UL simply will not cerify any 'proprietary' product as being 'safer' than its' competetors. For example, UL refrained from developing a standard for AFCI's until after the owners of the patent donated it to the public domain. The only monopoly we would ever endorse would be our own."
