They first need to come off of the endangered species list before the US will allow them to be kept. It all has to do with CITES and the agrement the US government has made with them. If you do not know what CITES is here is the website.
http://www.cites.org/
You could have a million signatures on the petition and it will mean nothing until the study of their natural habitat is done. On a side note did you look at some of the signatures and comments on that petition. The one person said it doesn't matter he'll buy them illegally and release them into the wild. If you want a petition to be taken seriously thats not the way to do it.