Hmm... If the argument is whether Muscovies are domestic or wild, I say look at the coloring and size.
Wild animals, fish and birds have a set coloring or pattern to their coats, skins or feathers. They also come in a set size. This is what survives best in the wild and variations usually get picked off in the wild.
Domestic animals, fish and birds usually have a wide variety of patterns and colors as well as different sizes, ans sometimes head and body shapes.
And I don't know of very many wild creatures that are white all year round, summer and winter. The arctic species all shed to a more somber colored summer coat when they shed their white winter coats. Polar Bears are an exception, but they are at the top of the food chain.
Usually, white or albino prey animals are dinner very quickly if they survive at all.
Muscovy breeders have muscovies of many colors and patterns, including brown, blue, solid, striped (ripple), spotted (pied) and WHITE.
So, would someone please tell me again, HOW are these birds wild?