Welllll, technically, it was not used in the right context. In-sha'-allah means "when god wills" but cannot be used in the way Biden did it because he used it as a question. I have never heard Inshallah be used as/in a question except when someone asks you to say Inshallah (as in, pressing you to "say Inshallah" so you either finish business or "move on".) I understand why Biden might have used it wrong in this context. If you take the literal translation, it could fit: "When? When god wills?". Inshallah is however often used to convey something that will never happen or only happen if god wills it (which is sometimes, a miracle). So, again, I kinda understand why Biden said it. But it doesn't really work. A much nicer arabic term is "Ta yenawwer el-milih'" which means "when the salt starts shining". This term definitely means "never" and is similar to "when pigs fly" or something from the west.