T先生に尋ねたら、以下の箇所をご指摘いただく。

In short, a lexical item is to be regarded as a correspondence rule, and
the lexicon as a whole is to be regarded as part of the PS-SS and SS-CS
interface modules. On this view, the formal role of lexical items is not
that they are “inserted” into syntactic derivations, but rather that they
license the correspondence of certain (near-)terminal symbols of syntactic
structure with phonological and conceptual structures.
(Jackendoff, 1997, The Architecture of Linguistic Faculty, pp. 89-90)

なるほど。的確なご指摘。わかりやすい。