As a political protest, this would likely be protected speech. Free speech is after all supposed to be the rule, not the exception. I am surprised though that a professional politician and his staff could be so out of touch with the web that they never registered their names as domain names.
This was my first reaction. People visiting the web and seeing all kinds of SOPA/PIPA hate, now will automatically assume these same guys support SOPA.
Better would be to redirect them to a page that says, THIS GUY SUPPORTS SOPA/PIPA.
Best would probably be to not squat on the domains.
(a) unimpressive, because it's obvious that you went and registered a bunch of domains with a version of their name that they don't use (christopher, benjamin, melvin, middle initial, etc), and
(b) a bad idea, because at best it's lulz for geeks in the know, but at worst it's "SOPA opponents have gone too far: they hacked web sites of the U.S. government!"
Not to mention confusing.
[1] http://en.m.wikipedia.org/wiki/Passing_off