Hoji 2006 is also available
here.
One of the main points of Hoji 2006 is that Saito's (2003) use of
so as the intended bindee in bound variable anaphora results in the impossibility to attain further testability with regard to local disjointness effects (i.e., the effects of so-called Principle B of the Binding Theory), because
so by itself cannot be used as an argument; see Hoji 2006: 4.1.4.