Um, yeah. Sign being a complete language is one of the tenets you must swear to for acceptance into the secret brotherhood of linguists. Oops. I had a roommate in college who served a mission to the deaf and we talked about it a lot.
So when we are talking of a pidgin, this means a language learned by an adult to get along just as well as they need to with another population that speaks a different language. Then creolization generally occurs with the next generation, and describes the languages of Haiti and the Dominican Republic. I suppose this may have been an issue Card had to address books 5 and 6 of the Alvin Maker series. Rien would have been a pidgin speaker while Marie would have been more of a creole speaker. I have no idea whether he got it right.
It also explains the manner in which Black English, while seemingling grammatically poor, is actually linguistically complete. There are grammatical rules to the ways in which it diverges from "standard" English. While I recognize this, I don't think it helps kids to conduct their education in that language with the possible exception of learning math.
I think Sign is essentially a creolization as well. It began as a translation of whatever language, but whenever kids learn a language their brains fill in grammatical elements that were missing if the language being taught them is not "linguistically complete". At least, this is what they were teaching when I was in college.
Some deafness occurs along with other mental disabilities, which is why deaf people are so sensitive about the issue.