250.30(A)(6) does not address the requirement of 250.24(B).

Does that mean where the 480V 3Ø secondary of an exterior pad-mount SDS does have the Xo terminal grounded ( bonded ) to the transformer case and to a grounding electrode { is now actually an 3Ø 4W system} does not need the grounded conductor to be extended to the first disconnecting means within a building ?

Is an existing system and cannot determine if the grounding jumper as noted above, [ and maybe intended to be 250.30(5)] actually goes to the building. Only the 3Ø conductors are in the conduit leaving the transformer enclosurer, thus, is not run with the derived phase conductors.