What are you talking about? Court's do it every day. They just base it on the 5th and 14th Amendments rather than the 9th. Barnett's approach at least forces the Court's to look to original intent in guiding the identification of these rights.
They do not do it under the Ninth. They never have.
Having the power to define rights, and what is and isn't a right, under the Ninth is their Holy Grail.