Feh. Since the nature of joined Trill as a concept was so severely adjusted between TNG's "The Host" and Dax's introduction on DS9, I say drop the entire transporter weakness altogether. Dr. Crusher et. al. were boggled by Odan's nature, and yet we later saw that, among other things, Curzon Dax was well-known throughout the Alpha Quadrant, Emony Dax was on Earth 100 years earlier (and bagged Dr. McCoy to boot!) and that Mayweather was familiar with the Trill homeworld yet another 100 years earlier. Clearly the general level of knowledge about joined Trill has been far more extensive than portrayed in "The Host".

As an alternative, one could assert that all joined Trill have the transporter weakness, but only when they've concealed their joined nature from the transporter operator (as Odan was obviously doing).