(To remove confusion, I don't believe Roeder or anyone should be waterboarded. But the logical extreme of those who support torture would give you the answer "yes.")
I'm getting to this late, but Jack Balkin (h/t Hilzoy) has some excellent questions about George Tiller's alleged murderer Scott Roeder:
"(1) Should the United States be able to hold Roeder without trial in order to prevent him from returning to society to kill more abortion providers? If we believe that Roeder and other domestic terrorists will plan further attacks on abortion providers and abortion clinics if we let them free, can we subject them to indefinite detention?