Does support mean signing up?

From Maggie Mahar's piece arguing that the media are being unduly critical of Obamacare:

The Media’s One-Sided Coverage of Obamacare | Health Beat by Maggie Mahar: "It is worth noting that the law draws the greatest support from people 18-34 (38 %) and 51-64 (41%.)  Somehow most in the media are ignoring the fact that so many young Americans favor the law—perhaps because that would contradict assertions  that 20-somethings and 30-somethings won’t be signing up for insurance."

I am not sure that supporting the law means that young people will sign up for it. Maybe they support it because they have not signed up for it yet. Maybe they don't realize that they have to sign up for it and that it is going to cost them something, probably more than they expect.