Um, that is actually wrong.
I just realized: when I looked for information on "duck" genetics, I found information on mallard-derived ducks, but because muscovies are a different species they have some different color genes.
https://alsquackery.com/muscovy
According to this, "lavender" in muscovies is caused by a different gene (they are calling the color "lavender" and the gene "pastel.") And blue is caused by a gene that works the way I expected it to, just like in chickens and in mallard-derived ducks.
So crossing a blue female with a lavender male should give black babies that carry the lavender gene, and blue babies that carry the lavender gene. No chocolate, and no sexlinks.
Sorry about getting it wrong the first time