I'm willing to accept the possibility—if not the probability—that, in earlier decades, the model was more inspirational to the general public than it is today. If make-believe artifacts are to go in the museum for other reasons, like telling historical narratives, then amend the mission statement. It's really clear cut.
I think you're taking the whole "mission statement" thing too literally. I doubt they weigh every single item against the exact letter of their mission statement before deciding whether to display it. I assume it's just a general set of guidelines, and actual decisions are made on a case-by-case basis. You could probably find a whole bunch of items on display there that wouldn't fit a strict, legalistic interpretation of their mission statement. Which is why that's not what the mission statement is for. It's intended to be a launching point, not a set of restrictions.
I also disagree with your interpretation of the mission statement as written. I've already explained why I think the Enterprise
miniature is indeed "of historical interest and significance to the progress of aviation and spaceflight," for reasons that have nothing to do with the shifting tastes of a fickle public. So I don't see any need to amend anything.
As for who am I to say it doesn't belong there? Well, first of all, I never said it doesn't belong there, did I? And second of all, who would I have to be anyway to have an opinion about where it should go? Everyone has a right to believe it doesn't belong where it is. It's appalling that that should be called into question.
That's not what I meant. I just meant that I don't understand your reasoning. The NASM is where it's always been, and the museum's own operators have always been fine with that. I'd call that sufficient precedent to justify its inclusion there. If it was deemed historically significant before, I don't see how it would stop being historically significant just because the show isn't as popular these days.