On ST:TMP, Captain Decker had said; All those vessels were call Enterprise. Were, is a past tense word. Meaning that the Constitution class looking starship in the picture is not the same Enterprise as the one they are on, but a different ship.
I believe you are the first person ever to speculate that the TOS Enterprise NCC-1701 and the TMP Enterprise NCC-1701 are two totally different ships, when the creators of TMP, the producers of Trek since then, and all fandom since has agreed that one was a refit of the other...simply because of Decker's (ambiguous?) choice of words?