Besides, that's a Starfleet Command logo on the left side, and the typeface of 'Constitution Refit' and the minimalist white-on-black display also fits what we've seen of the recycled console displays that made it from Phase II to TMP/TWOK. It just...feels right, somehow.
Which is exactly what someone trying to create a fake would intend.
I mean, think about it. If this were intended as some kind of MSD, why would it have an inset of the old design? It looks more like somebody found a comparison cutaway drawing on the Internet and faked it up to look like an MSD graphic.
It's also worth noting that "Constitution" was not officially established as the class name of Kirk's ship until TNG. It had been suggested by various production documents and fan references, but it wasn't official at the time of Phase II
Also, the version of the UFP seal there is not the same one used in TMP graphics. I checked by Star Trek: The Motion Picture Peel-Off Graphics Book
by Lee Cole, and the UFP logo she designed for TMP had smaller "laurel leaves" that only went about halfway up the circle, and the "United Federation of Planets" around the outside was on the top in larger print. It's similar enough that maybe it could've been an early draft, but different enough to make me skeptical.
I looked at the original link, and the text says it's "a fan-made reproduction of the Master Systems Display (aka "MSD") of the Refit Enterprise from Gene Roddenberry's failed second TOS series." Now, that's highly questionable right there, because as I said, the term "MSD" did not exist until TNG. It's a failure of research at best. If they use a term that didn't exist at the time, then why should we trust anything else about the claim? Especially when it admits that it's fan-made. Maybe they're just wrongly assuming it's a replica of a real prop, or maybe they're falsely trying to pass off something from a fan's imagination as something that was part of an actual production.