The fact that the hull originally had a Scimitar turret on it is irrelevant, it now has a Scorpion turret on and is therefore a Scorpion.
My Sabre started out as a Scorpion but now has a Fox turret on it, but that doesn't make it either of those - it's now a Sabre..
The tank argument has been done many times before, and I suspect Tony has tongue firmly in cheek...!