This is pretty clearly a star wars analogy right down to the jedi/star powered that stand against her. Its also a fairly reasonable synopsis of every empire that has ever existed on earth. They rise, they have a golden age, then they decay and fall apart, for reasons both internal and external. Her argument is probably a true one, as far as it goes, but just because in a thousand years the empire might become bloated and decayed is no reason to do away with it now. Its like saying, "You know that delicious fruit will spoil eventually right? Then why bother eating any of it now?"
On the other hand, she provides an interesting outlook very different from "ours" in that she comes from a race thats functionally elvishly unaging, or "timeless space" has some sort of odd temporal effect where she can watch ages go by in a regular lifetime. Its clearly not a stasis because they have to rebuild after each failed invasion, but the idea that she basically gets to watch time go by in fast forward is an interesting one, as it would have an effect on how she perceives the value of things created. If you build something that lasts decades, to her it might as well be a sand castle built at low tide. It will be gone so fast as to be meaningless. Even an empire of a thousand years is not so much as a single generation to her. Imagine if you watched as every nation on earth rose and fell every 20 years or so. You wouldnt have much respect for how they were governed would you?