Is it a firecracker if you never light the fuse?
A Rose, by any other name, would smell as sweet.
If it walks like a duck and quacks like a duck....
I've given this some thought. When I used to build plastic models, the Revell Kit would say "Plastic scale model Saturn V" -- I don't think the word rocket ever appeared on the box. Clearly, it was a rocket, but it made no claim to that title if it was a plastic display model. I also note that most of the rockets I have built in the last year all say "Flying Model Rocket" on the packaging, to indicate that this does, indeed, fly.
Yet, we do make distinctions -- for example, a "bullet" isn't really a bullet until AFTER it has been fired. Before that time, it's a "round" or "cartridge" because it consists of a package of components together that, once fired, becomes a projectile because the foward section has been shoved through the barrel by the explosive force of the rest of that package.
Similarly; a rocket becomes a rocket only when the explosive force of the rest of the package turns the rocket into a projectile. Before that time, it's a flying model or potential flying model. Can we call it a rocket if it's never flown? Sure, but only in the same way that we can call a cartridge a bullet if it's not been fired. It is technically incorrect, but colloquial english allows us to use the term regardless for the sake of expediency.