I believe this figure is intentional. Apart from Tocqueville being a lucid writer with a great command of the pen, it also includes repetitio on “America.” If he wasn’t consciously intending these figurae to express the brilliant aphorism, then he gives us little more than redundancy, which he is not given to do.
A. America is great
B. because America is good,
B. and if America ever ceases to be good,
A. America will cease to be great.