I don't think the U.S. Constitution bans anyone from getting a title from some random French family, only from a "King, Prince, or foreign State".
Is this article intentionally misrepresenting? There's plenty of scummy things he's done without having to invent weird distractions.
Exactly how does it apply? It didn't come from a "King, Prince, or foreign State". I could declare that I grant you a title, but because it isn't coming from a monarch it's meaningless and that article doesn't apply.